Waiting for my secondment, I can affirm that, so far, one of the nicest parts of the SPEAR project are the
training sessions held periodically in one of the partner institutions.
Last week, I met with all the other ESRs in Gothenburg. We had the chance to assist to precious talks on
unconventional computing, a topic that has always attracted my interest and from which I could also find some hints for my project.
It has also been particularly stimulating to hear from professor Akerman about the story of his
startup, Nanoosc, since the real world of startup is sometimes fascinating but obscure to most of us.
For the first time, also all the PIs were presents. This gave us the opportunity to present our work to
a specific audience, and we could receive interesting and original feeedbacks.
The weather has not helped the visiting experience, but on the last afternoon, we could give a look to this nice town and enjoy some time together. After one year, we start to know each other better and these events are getting better also on a personal level
An important part of PhD life is maintaining devices you are supervising. For example, besides other devices, I am responsible for our atomic force microscopy (AFM). This type of microscope uses a fine tip to characterize a surface with up to picometre precision. In comparison to scanning tunnelling microscopy, the feedback is generated from changes in cantilever properties rather from a tunnelling current. In my group, mainly use the so-called tapping mode, where the cantilever is resonantly driven and the change of the resulting amplitude due to the close by sample is used as feedback. This way of imaging a surface is advantageous since it reduces the force exerted on the sample.
Image of the unmounted AFM body with view on the optics. The scanner was removed before and is shown on the right. The problem was a loose connection between the two components.
Recently, our roughly ten-year-old machine was experiencing some troubles. Occasionally, the scanner was not detected any more when the scanning unit was moved. It is designed that way, that the scanner needs to be pulled out to exchange the cantilever with the tip. A semi-flexible multilayered PCB cable connects the scanning with the mainboard of the AFM. The dynamic-cyclic loading degraded this cable over time. To confirm our first assumption, I took the AFM apart, removed the cable and checked if the pins on both ends are all still connected. As expected, depending on the bending, several pins are shortcut and several lose their connection.
Cable connecting the AFM mainboard and the scanning unit.
After reassembling the entire unit and making a few minor adjustments, the AFM will work fine until the replacement part arrives. Finding these temporary solutions is an important lesson during the doctoral studies, as it enables a variety of technical problems to be solved, whether just as a bridging solution or a complete repair. For my research, atomic force microscopes are a useful tool to measure the thicknesses of exfoliated crystals, to clean surfaces of flakes or flattening heterostacks as shown in the following images.
Left: GIF of the polymer residue cleaning of a WTe2 device encapsulated by hBN with contact mode scanning. Right: High resolution scan of the same device double layer WTe2 after cleaning.
The new year started with my academic secondment at ETH. Had a chance to catch up with Marco (ESR3) before he left for his secondment in Grenoble. While Niklas (ESR4) has been constantly there to help me with the institutional and lab stuff. I also had an opportunity to meet my industrial secondment supervisor Dr. Jan Rhensius from QZabre. Zhewen (ESR13) is also around to show me nice trails just behind the ETH Hönggerberg campus.
How can I forget watches, probably the strongest attraction that always pulled me towards Switzerland. Zurich is one good place to see watches thanks to the famous bahnhofstrasse, one whole street full of watch boutiques is no less than a watch paradise. Every week I go to the street to update myself with the new watches on display but still feels like I haven’t seen it enough. Apparently there is a watch museum here which I haven’t managed to see but planning to see soon, never the less I did visit the Lindt chocolate museum. I would recommend to take the guided tour, it’s a fun experience to eat free chocolate like kids.
World’s largest free standing chocolate fountain at the museum
The Journey of Homecoming: Reflections on a Chilean Vacation
More than a year of the Ph.D. passed so quickly that I barely believe the first year is already over. This first year has been full of exciting adventures and amazing new friends. Initially, this post would have been a sum-up of my first year, both adventures and successes. But, with the first draft, I realized I was not going to do justice to all the great things that happened this year and to include the biggest realization I had this year. Therefore I decided to focus on my vacations in Chile.
I stayed in Santiago for a few days to meet many friends, and the feeling of closeness had not disappeared with any of them. Moreover, with a group of friends with whom I gather daily to play online games and chat. Now that we were in the same city again, since most of us left the country after the pandemic, we had a wonderful barbeque just in time to see the Word cup final and celebrate for our neighbors! After this, it was time to go to my hometown with my mom and sisters. Over there, I met my dad, and the crying came back with no less intensity. I will never forget the long hug and the feeling of finally being home. Here we stayed a few days before continuing the trip even souther to see my brother in Llanquihue. This meeting was the most emotional since it was the very first time all six of us were together to spend New Year’s as a family since I left, and most probably, the last time until the end of my Ph.D. We spent the most relaxing weeks in Llanquihue, enjoying the lake, mountains, and weather of the south of Chile. Thereon, the goodbyes were in order, so undoing the route back to Santiago, I saw most of my friends and family members. When I went to take the flight, I realized that my heart was full of love (and food), so I started missing my family as soon as I had to say the final goodbye at the airport door.
New Year’s with the Leiva Montecinos
Upon arriving in Halle, I had the strangest feeling since, from the minute I was out of the train station, I felt at home again. The last year and a half showed me that home is not a place, but the people with whom I feel at home. I am forever thankful to SPEAR since it taught me not only physics but also how to enjoy living abroad and the importance of good friends and colleagues.
Silly me, thinking that a Ph.D. was only to learn about science. Here I am, with tears again, prost to Halle and the SPEAR program!!.
Right before the 2nd ESR training event in IMEC, Leuven, I went back to Aachen, where I had spent 3 unforgettable years, to participate in the long overdue master’s graduation ceremony. The festival was a one-day event, filled with a variety of activities including exhibitions of academic work, live performances, and group photos of graduates. The highlight of the festival was the graduation ceremony, where the student received their degree certificates with pride and joy. I was so excited and so lucky to additionally be awarded the ‘Springorium Commemorative Medal’ for my Master’s degree with distinction in materials science. The city mayor and the university president also participated in the ceremony and delivered great speeches. A variety of cultural and entertainment shows were also performed by the students.
2022 RWTH Graduation Ceremony [Image is taken from https://www.rwth-aachen.de/cms/root/Die-RWTH/Aktuell/Pressemitteilungen/September/~wwgwb/RWTH-feiert-stimmungsvolles-Graduiertenf/lidx/1/]
Aachen is a city overflowing with culture, history, and innovations. It is also a very tolerant city, where people speaking different languages and having different backgrounds gather together here from all over. I am so grateful that I have lived here for years, have studied with plenty of smart brains, and have made lots of friends with whom I share considerably unforgettable memories.
For the past few months since I started my work here in Gothenburg, the weather has been rainy at least half of the time! Even for me who loves the rain, it can get annoying sometimes. On the other hand, long winter nights would severely affect the energy level of someone without a routine to stick to (and of course, vitamin D pills!). Thankfully, it was easier for me as I am busy with the measurements and cleanroom training almost all the time, and I can’t really feel how fast the days pass by.
Although I still have to get the licenses for the cleanroom tools, I am being trained and partially doing fabrication with the help of one of our postdocs who is also mentoring me. Coming from a simulation background, it truly fascinates me how I can fabricate real-life devices and measure them. Last week we finished my first simple spin Hall nano oscillator chip and since then, I’ve been doing auto-oscillation measurements on it to determine the signal (and the device) quality. If everything goes well, we will fabricate Memristive gates on top of them, which is a very complex procedure. Afterward, we will investigate the effects of those Memristive gate’s position and shape on spin Hall nano oscillator chains and arrays.
A picture of the device that we’ve fabricated (I accidentally scratched it during the development! Thankfully it works fine).
The new year has begun but I cannot forget the last months of 2022 where I spent 3 months in Halle at the Martin Luther University as a part of my secondment. I was in the group of Prof. Ingrid Mertig at Halle and had some fun time learning micromagnetics and atomistic spin dynamics simulations.
Time with Ismael (ESR 10) and Sergio (ESR 9) just went so quickly. We had a lot of fun besides work! A lot of group activities was something I am really gonna miss there! 3 months is a small amount of time to be able to do something significant in a completely new field. As I had never done micromagnetics or atomistic simulations before, it took me some time to get into the process. Nonetheless, I got to see how theorists think and what kind of approach they have in magnetism compared to experimentalists.
I was also fortunate to be able to give a talk at the MPI, Halle as a guest PhD student on my experimental work. The MPI and MLU are closely located and there is a good amount of collaboration there. I am looking forward to get back to Halle for one of our next SPEAR meetings in September this year!
Have you ever thought about why we can not perform brain tasks on our computers? Well of course I don’t mean a simple cat/dog recognition, or calculus (Computers have been specifically designed to do a very limited number of brain functions extremely well – even better than humans), but something bigger like analyzing new and unfamiliar situations.
To answer this question, let’s first see how conventional computers work:
Simply explained, there are two main units: a processing unit to process and analyze the data and a memory unit to store them. These two blocks are separated from each other and every time that a task must be done, the data should go back and forth between these two units. This architecture is known as Von Neumann architecture [1].
Fig1: Von Neumann architecture: in a conventional computing system, when an operation f is performed on data D, D has to be moved into a processing unit, leading to significant costs in latency and energy [2].
As you’ve already found out, there are two issues with this architecture that makes it almost impossible to do heavy tasks with:
Energy consumption, as the blocks are “separated” and lots of Joule heating can happen in between.
Not fast enough, due to the time required for the data to go back and forth.
This is also known as the Von Neumann bottleneck [3]. In other words, the architecture causes a limitation on the throughput, and this intensive data exchange is a problem. To find an alternative for it, it’s best to take a look at our brain and try to build something to emulate it, because not only is it the fastest computer available, but it is super energy efficient.
The brain is made up of a very dense network of interconnected neurons, which are responsible for all the data processing happening there. Each neuron has three parts: Soma (some call it neuron as well) which is the cell body and is responsible for the chemical processing of the neuron, Synapse which is like the memory unit and determines the strength of the connections to other neurons, and Axon which is like the wire connecting one neuron to the other.
Fig2: Neural networks in biology and computing [4].
Neurons communicate with voltage signals (spikes) generated by the ions and the chemicals inside our brains. There have been many models presented on how they work, but here will be discussed the simplest (and probably the most useful) one: The leaky integrate and fire model [5].
Fig3: leaky integrate and fire model, Incoming pulses excite the biological neuron; if the excitation reaches a threshold, the neuron fires an outcoming spike, and if not, it relaxes back to the resting potential [6].
As it was said earlier, neurons communicate with spikes which can change the potential of the soma. If a spike from a previous neuron arrives at a neuron after it, the potential of the soma increases. However, this is temporary, meaning that if no other spikes arrive afterward, the potential of the soma will reach the relaxed level again (leakage). On the other hand, if a train of spikes arrives at the neuron, they can accumulate (integrate) and if the potential reaches a threshold potential, the neuron itself will generate a spike (fire). After firing, the potential will again reach the relaxed level.
Apparently, the connections between all the neurons are not the same, and the differences are in the synapses. The form and combination of the synapses change in time depending on how active or inactive those two neurons were. The more they communicate, the stronger and better their connection, and this is called “synaptic plasticity”. (This is why learning something new is so hard because the connections between the neurons need time and practice to get better!). For more investigation into the fascinating world of the brain, this book is recommended: Neuronal Dynamics: From Single Neurons to Networks and Models of Cognition [7].
Now, it’s time to get back to the Von Neumann bottleneck. With inspiration from the brain, it can be seen that it’s better to place the memory unit in the vicinity, or even inside, the processing unit (just like the soma and the synapses which are really close), this way so much time and energy can be saved. It is also obvious that the processing units are better to be nonlinear as in the brain, and the memory unit should be able to be changed or manipulated to mimic the synaptic plasticity. We know how different parts should behave in order to have a computer to at least function like the brain, but the big question is: What hardwares should be used? What kind of devices act like a neuron, or a synapse? And even if we find them, are we able to place them close to each other to overcome the Von Neumann bottleneck?
These are the questions that Neuromorphic computing tries to answer. In other words, it is an attempt to build new hardware to be able to do computing like our brain. Some of the most promising candidates here are the spin-orbit devices as they are super-fast, energy-efficient, and more importantly, nonlinear [8][9]. I will talk about them and their major role in this field more in detail in the second part of my post soon!
1. Von Neumann, J. Papers of John von Neumann on computers and computer theory. United States: N. p., 1986. Web.
2. Sebastian, A., Le Gallo, M., Khaddam-Aljameh, R. et al. Memory devices and applications for in-memory computing. Nat. Nanotechnol. 15, 529–544 (2020).
3. John Backus. 1978. Can programming be liberated from the von Neumann style? a functional style and its algebra of programs. Commun. ACM 21, 8 (Aug. 1978), 613–641.
4. Bains, S. The business of building brains. Nat Electron 3, 348–351 (2020).
5. Brunel, N., van Rossum, M.C.W. Lapicque’s 1907 paper: from frogs to integrate-and-fire. Biol Cybern 97, 337–339 (2007).
6. Kurenkov, A., DuttaGupta, S., Zhang, C., Fukami, S., Horio, Y., Ohno, H., Artificial Neuron and Synapse Realized in an Antiferromagnet/Ferromagnet Heterostructure Using Dynamics of Spin–Orbit Torque Switching. Adv. Mater. 2019, 31, 1900636.
7. Gerstner, W., Kistler, W., Naud, R., & Paninski, L. (2014). Neuronal Dynamics: From Single Neurons to Networks and Models of Cognition. Cambridge: Cambridge University Press.
8. Grollier, J., Querlioz, D., Camsari, K.Y. et al. Neuromorphic spintronics. Nat Electron 3, 360–370 (2020).
9. Zahedinejad, M., Fulara, H., Khymyn, R. et al. Memristive control of mutual spin Hall nano-oscillator synchronization for neuromorphic computing. Nat. Mater. 21, 81–87 (2022).
Ferroelectrics are a category of material that in absence of an external applied voltage they still show a remanent polarization. The reason can be found in their atomic structure. For example the family of perovskites are ferroelectric material due to their specific crystal arrangement. Perovskite all share this similar ABX3 structure, where usually the X is oxygen and the A and B represent two different metals.
Fig.1 Phases of KNbO3 (potassium niobate) at different temperatures. It shows some structures where is possible to have a remanent polarization due to non-centro symmetry of the Niobium atom (in green) inside the cubic structure. When the Niobium atom is exactly at the center (in this case above 708 K) the material is not anymore ferroelectric [1].
One of most famous and studied is lead zirconate (PbZrxTi1-xO3) commonly called PZT. One of the biggest issues with this material is the toxicity due to the presence of the lead. For this reason, researchers focused on finding a material with similar characteristics. So many of them came out like barium titanate (BaTiO3), know as BTO or strontium titanate (SrTiO3) known as STO. In the picture here above another example of a lead-free perovskite material: potassium niobate (KNO3).
The remanent polarization properties is given by the presence of an atom inside this cubic-like structure that is not exactly at the center but slightly shifted. This non centro-symmetric structure give rise to a non-compensated positive charge of the body atom (Ti or Nb for example). The ferroelectric properties then are just given by the presence of the non-compensated charge when all the external voltages are removed. The temperature has an important role since for every material, for a given energy the structure tend to become a symmetric body centered cubic structure, hence there is a critical temperature after which the ferroelectric materials become paraelectrics. In this state they still react non-linearly to an external applied field but they do not show a remanent effect in absence of it.
Fig.2 Behaviour of a dielectric, a paraelectric and a ferroelectric material under an applied external electric field [2].
The polarization bistability for a zero external applied field is the key feature that makes ferroelectrics good candidates for memory applications. In recent year, many studies focused on integrating the ferroelectric materials in order to create new memories, more competitive from an energy computation point of view or overall faster writing and reading speed as FE-Fet [3], FE-RAM [4] or MESO [5] and FESO [6]. If for the first two the ferroelectric properties are aimed to improve the properties of already existing devices, like transistors or non-volatile random access memories; for the MESO and FESO case the aim is more ambitious. The idea is to develop a new logic based on spin controlled by ferrolectric non-volatility.
Recently, others materials showed to have ferroelectricity properties like Germanium telluride (GeTe), Indium arsenide (InAs) and many others. These materials show a simpler combination of only two atoms and that are not insulating like perovskites (sually they are metalic or semiconducting).
The bigger advantage is the possibility to pattern them in order to produce nanodevices, given by an higher durability when subjected to nanofabrication steps like etching. This one tend to destroy the crystal structure and hence the properties of the insulating perovskites . As a consequence, these new materials bring the ferroelectric-based devices a step closer to mass production and adoption.
If we take into account the case of germanium telluride, the ferroelectricity comes from the unusual bonds between germanium and tellurium layers. They tend to form a stronger bond with a neighbour layer with respect to the other forming a bilayer structure that is not symmetric (see pictures below). Similarly under an applied electric field the structure reorganize, causing the polarization to change sign (if the field is strong enough). It can be also seen as the germanium in the center of the cell moving along the larger diagonal of the deformed cubic cell (also called rhombohedral cell, left picture).
Fig. 3 Left: Cell structure of Germanium telluride (yellow Germanium, blue tellurium). Right: Switching mechanism: a) stable configuration of layer of Germanium (yellow dots) bonded to Tellurium ones (in red). b) when an electric field is applied, an unstable state appear where Germanium is bond to both top and bottom Tellurium atoms. c) Final state in which the Germanium atoms will be bond to the Tellurium atoms in the upper level with respect to the initial state [7]
So in a similar way to perovskites germanium telluride is know to show a remanent polarization at room temperature that can be controlled by an external applied electric field.
I hope you enjoyed this small talk on ferroelectrics, I will write in future a part 2 to explain the relation between ferroelectricity and spin-logic based devices. For further information you can email me at: salvatore.teresi@cea.fr
References
[1] P. Hirel et al., Phys. Rev. B 92 (2016) 214101.
[3] Stefan Ferdinand Müller (2016). Development of HfO2-Based Ferroelectric Memories for Future CMOS Technology Nodes. ISBN 9783739248943.
[4] Dudley A. Buck, “Ferroelectrics for Digital Information Storage and Switching.” Report R-212, MIT, June 1952.
[5] Manipatruni, S., Nikonov, D.E., Lin, CC. et al. Scalable energy-efficient magnetoelectric spin–orbit logic. Nature565, 35–42 (2019). https://doi.org/10.1038/s41586-018-0770-2
[6] Noël, P., Trier, F., Vicente Arche, L.M. et al. Non-volatile electric control of spin–charge conversion in a SrTiO3 Rashba system. Nature 580, 483–486 (2020). [7] A. V. Kolobov, D. J. Kim, A. Giussani, P. Fons, J. Tominaga, R. Calarco, and A. Gruverman, Ferroelectric switching in epitaxial GeTe films, APL Materials 2, 066101 (2014).
[7] A. V. Kolobov, D. J. Kim, A. Giussani, P. Fons, J. Tominaga, R. Calarco, and A. Gruverman, Ferroelectric switching in epitaxial GeTe films, APL Materials 2, 066101 (2014).
This summer I was invited to a talk in San Diego, California (USA) to show a recent work of my group on Bilinear magnetoresistance effect in mercury telluride (HgTe) a topological insulator. It was an important event since I had to make a presentation in front of « experienced researchers » in the field of Spintronics.
It was a giant conference where only a part of it was dedicated to Spintronics. I had the pleasure to meet some researchers that are currently revolutionizing the spintronic field like Henry Jaffres or Dongwook Go (a young scientist working on a new phenomenon called Orbital Hall Effect). It is always a good opportunity to catch up on all the news in our field.
I took the opportunity to visit not only San Diego but also cities like Los Angeles and Santa Monica. I am not a big fan of the States but I would like to say that San Diego and the state of California is worth visiting. Furthermore in California there is the Silicon Valley, it was a big opportunity to look for a job after the PhD. For this purpose international conferences are a good opportunity to start to be known as a (hopefully) good researcher (and scientist) in the international community.
Here is below a picture of the ferris wheel in Santa Monica Pier
SOT-MRAM is a promising candidate for next-generation MRAM, as it features switching of the free magnetic layer done by injecting an in-plane current in an adjacent SOT layer. After I joined IMEC last year, my research topic focused on the SOT-MRAM, especially reducing the operation current of SOT-MRAM. Among many solutions, putting serval pillars on one shared SOT track is a genius idea. Firstly, the multi-pillar design can increase integration density. In conventional single-pillar devices, one pillar needs at least two transistors. While in multi-pillar devices, the number of required transistors per pillar can be reduced to (1+1/N), where N is the number of pillars. The reduced number of transistors can effectively save the space and improve the density of devices.
The schematic of a 4-pillar SOT-MRAM device
However, if we think that the 4 pillars on the same SOT track are totally the same. All pillars will be switched together under a SOT current. Here, combining the voltage-controlled magnetic anisotropy effect, we can lower the operation SOT current by applying a positive voltage on a certain pillar. When we want to switch a pillar, we just need to apply a positive voltage on this pillar and apply a proper SOT current. In this case, we can not only reduce the operation current but also realize the individual control of each pillar even if they are located on the same SOT track. The story of multi-pillar SOT-MRAM has just begun…
Learning about spin orbit torques in Leuven and also having fun in Leuven. Leuven, Belgium, 2022
We recently had the wonderful opportunity to learn about spin orbit torque technology at IMEC, a world-leading R&D and innovation hub in nanoelectronics and digital technologies in Leuven, Belgium. During our time there we had a series of enlightening spin orbit talks, giving us a great overview of the current state of the technology in terms of real world applications as well as some more fundamental considerations. We also got the chance to tour the cleanroom facility at IMEC, which is a genuinely impressive construct although unfortunately we’re not allowed to share pictures of it on the blog. As well as the scientific content we also did a series of classes on how to improve our scientific communication skills (although blog posts, alas, were not specifically covered). This was a great opportunity to improve not only our communication skills but to hear about the scientific exploits of the other ESRs. Although learning obviously occupied most of the trip, we did find time for a brief interlude of socialisation during which ESR4 ate an amusingly large amount of rice. Look at that stack of dishes! Classic ESR4, never change.
European School of Magnetism – Two weeks of training, fun and friendships
What happens when you take around a hundred students working in the field of magnetism and put them in the same place? You end up with a mix of intriguing ideas, intense discussions, heated sports sessions, and lots of fun. This is how I would describe the two weeks in the mid of September spent in the European School of Magnetism (ESM) in Saarbrucken. It was a nice opportunity to meet new people, form new connections and get together with fellow ESRs (Eoin (ESR1), Marco (ESR3), Salvatore (ESR7), Paolo (ESR8), Sergio (ESR9), Vishesh (ESR11) and Zhewen (ESR13)).
Me (ESR14), Salvatore (ESR7), Paolo (ESR8), Vishesh (ESR11), Zhewen (ESR13), Marco (ESR3), Eoin (ESR1) and Sergio (ESR9) during the European School of Magnetism in Saarbrucken, Germany
Leading professors and researchers from various fields of magnetism gave lectures on topics ranging from fundamentals of magnetism to applications. I was fascinated by how some properties that we generally take for granted have such complex origins. It was also interesting to learn about the wide variety of magnetic materials (ferromagnetic, antiferromagnetic, ferrimagnetic, multiferroics, magnetocaloric, magnetoelectric, etc) and their wide range of applications. Some lectures were organized to give the participants an industrial perspective on the field of magnetism which were really helpful for people willing to go to the industry or start their own venture. Some volunteers from the participants were also given the opportunity to chair lecture sessions. I also had the opportunity to chair a session by Johannes Paulides on Electric motors and generators.
Chairing a lecture session by Johannes Paulides from Advanced Electromagnetics on electric motors and generators
We also had the opportunity to experience a day of practical experiments in the labs of Technische Universitat of Kaiserslautern and Institut Jean Lamour in Nancy. We were divided into groups and sent to one of the two institutions. My group got the opportunity some broadband ferromagnetic resonance (BB-FMR) measurements at TU Kaiserslautern. It was interesting to carry out experiments outside the scope of my project.
Since the theme for this year was “Basic magnetism for sustainable development”, a crucial element of the school was student projects to solve sustainability issues using magnetism. Along with Marco (ESR3) and other participants, our group tackled the issue of energy efficiency in computation using neuromorphic computing. We presented a range of magnetoelectric, spintronic, and magnonic devices and architectures that can potentially solve this issue. Overall, it was an amazing experience interacting with people from different backgrounds and working on different projects. Surely, the seeds of many potential collaborations and partnerships were sown over the food table, coffee breaks, poster sessions, and late-night discussions, which will reap rewards in the future. In my opinion, if you are working in the field of magnetism, you should attend a session of ESM during your Ph.D.
Last evening of the European School of Magnetism 2022
Last week I had the chance to join the Skyrmionics Retreat in Annweiler am Trifels. Not long after arriving at my remote destination, I found myself in this peculiar scenery straight out of a novel by Agatha Christie: a group of elite scientists secluded in a forgotten mansion in the forests of the german frontier with France. The place took just one day to become completely isolated from civilization due to the strong winds and rains that seemed to be waiting for all of us to arrive at our final destination. And I say final because something was forever lost in the dark forests that now populate my scariest nightmares.
It all started as a normal workshop about skyrmions: we talked about skyrmions, we showed simulations of skyrmions, we said “Dzyaloshinskii–Moriya” several times, and different people showed micromagnetic simulations of skyrmions dancing, playing basketball and even one paying its taxes. Everything was going fine, but at that moment I got distracted and I didn’t see the evident danger. For several days we mixed all these talks and discussions with billiard games and more relaxed topics in the evenings. The isolated mansion had a full pantry, so we managed to eat plenty and we didn’t bother about the dark forest that surrounded us every night, every minute of our sleep, always wet, always rainy, always expectant…
[Part 2 will come soon]
The Path leading to the mansion before the rain started
As I reach the ten-month Ph.D. mark, I feel that time in Halle moves a bit funny. It feels like it is moving slowly and fast at the same time. This contradictory feeling perhaps comes from the contrast between the tree leaves on my way to work and my research field. They are slowly turning orange as autumn approaches, contrasting sharply with the fast-changing research on skyrmions. As I try to make sense of how time progress here, I am learning many unexpected things. I even developed an unexpected project (more about that coming soon in another blog). However, the most important and surprising lesson is not all about skyrmions. It is instead the importance of talking to people.
As an undergrad student, I have always followed the standard recipe to learn a new thing, attend classes, and spend hours alone struggling with books or papers. For some time, it felt that the rest of my academic career would be like this. However, in the Ph.D., as we get closer and closer to the edge of knowledge about some topics, we cannot find things in books anymore. Therefore, we have to spend hours going through the scientific literature to understand a “simple” thing. We must learn the current state-of-the-art of the research field and the next steps we should take in our research project. I realize that we can learn a lot and fast by simply talking to people. I recently seriously thought about this while attending several conferences, such as the NeuroSpin summer school organized by our ESR3 Marco (excellent job, Marco!). I cannot emphasize how much I have learned by talking with Ph.D. students and Professors. Things that I have been struggling to understand for months become apparent, and research directions that I have not even considered become a new path. I guess I have always underestimated how a simple conversation over a coffee can shape everything. Of course, I always expected that discussions would be meaningful. Still, I have also underestimated the tremendous impact they can have on our research. During the pandemic, virtual meetings were useful; however, they cannot replace eye-to-eye discussions. I come back from conferences with many new ideas shaping my work. Talking to people… what an enjoyable way to learn. This is a lesson that I will carry for life.
In the spirit of talking with very smart people, it has also been a great pleasure sharing an office ESR 11 Vishesh and recently arrived ESR 12, Arturo. They are visiting my group for their secondments. Hopefully, I can continue learning from them, especially during our informal lunches.
What I like about the SPEAR network is that we are not only building a scientific network but also friendships and a support network. I have been preparing talks and posters with helpful criticism from Vishesh and ESR 9 Sergio, who have become dear close friends. Additionally, I received their support in the audience of my very first international talk, shown in the picture taken by them (with spoilers for my next blog).
It’s been almost two months since I moved to Sweden. Although I had a frustrating one-year delay due to all the admission issues and visa processes, it was totally worth it. Gothenburg is a wonderful city (at least in the summer!) surrounded by nature. In fact, it has been announced several times as the most sustainable city in the world.
Here at the MC2 department of the Chalmers university, I fit in the group so easily that I could never wish for a better environment. My friendly colleagues have been super helpful and supportive. Our scientific and non-scientific discussions during Fika time (a Swedish tradition almost the same as a coffee break with sweets) have inspired me a lot.
For someone who is coming from a simulation background, it’s not easy to learn the experimental techniques and instruments at once, however, I am doing my best! For now, I’m learning to work with different deposition and measurement techniques such as sputtering, AMR, FMR, and ST-FMR as well as taking cleanroom courses. So far, it has been a challenging yet valuable experience for me.
Despite the fact that I had just started my Ph.D., I decided to attend the NeuroSpin summer school at Lausanne. It was a pleasant opportunity for me to talk to professors and students with different backgrounds and it actually widened my point of view about the role of our field in future interdisciplinary neuromorphic computing applications. I also had a chance to finally meet with Marco, ESR 3, and Ismael, ESR 10, and had such an enjoyable time with their company both inside and outside the summer school classes.
Hello readers! This first post is about antiferromagnets. I talk about the general concepts in antiferromagnetism and then later I dive into some interesting complex antiferromagnetic states at the atomic scale! I hope you have a good read! Please feel free to reach me out at my email for any further questions! (vsaxena@physnet.uni-hamburg.de)
It was a great pleasure for me to co-organize the EPFL-ETH Zurich summer school “NeuroSpin school 2022: Spin based device architectures for neuromorphic computing and storage” from 22-26 August at EPFL in Lausanne.
This all-student-organized school had an active and enthusiastic participation of over 26 students from the ETH domain (EPFL, ETH Zurich, Empa, and Paul Scherrer Institut) as well as from all around Europe. The school was successful in connecting PhD students, master students and postdocs working in diverse fields from magnetism to organic electronics, machine learning and neural information processing. Despite working in different research fields, we came together with a similar vision of understanding and exploring horizons of unconventional and sustainable computing.
All participants and guest speakers of the NeuroSpin 2022 summer school in Lausanne.
We were fortunate to have guest lecturers from the backgrounds of computational neuroscience, spintronics, magnonics and artificial spin systems: Dr. Mihai Petrovici, Dr. Alice Mizrahi, Prof. Erik Folven, Dr. Naemi Leo, Dr. Kevin Garello, Dr. Aleksandr Kurenkov, Prof. Philipp Pirro, and Prof. Gyorgy Csaba. Their inspiring lectures as well as exercise sessions on different simulation and programming softwares were a golden opportunity for us to expand our skillset and knowledge sphere related to computing devices. Furthermore, the poster presentation, journal club session, panel discussion with all the speakers as well as plenty of individual interesting conversations with participants and speakers have definitely broadened our horizons regarding the emergent topic of spin based unconventional computing and we hope to draw benefits from this during our future research.
I was especially happy to reunite with my fellow SPEAR ESRs Maha and Ismael, with whom I spent many hours in scientific and unscientific discussions and who highly contributed to the great atmosphere at the school! I can’t wait to meet you again in Belgium soon!
Next to the massive scientific gain, personally, I also highly appreciate the experience of having organized such an event for a whole week which required nearly a year of preparation time to consider all different aspects necessary to hold a summer school.
As such a task is barely possible for one or few PhD students, I would like thank here my fellow organizing committee members (EPFL: Shreyas Joglekar, Andrea Muchietto, Mohammad Hamdi; ETH/PSI: Laura van Schie, and Zhentao Liu) for the joint efforts during the last year! Also, all the guest speakers and participants deserve my gratitude for showing high commitment and dedication to this school and establishing a great atmosphere in which everyone was happy to learn more from anyone else. Lastly, many thanks to the Doctoral school of EPFL (EDOC) and ETH Zurich for giving us this great opportunity to organize the school and the supporting professors Dirk Grundler (EPFL) and Pietro Gambardella (ETHZ) for their advice and guidance! I am looking forward to more of such events in future!
In the end of June I had the chance to present a poster at the ISAF conference, in Tours, to which I participated together with my supervisor and with a colleague. It was my first in-person conference, the poster was about a theoretical work I started during my internship and that I resumed at the beginning of my PhD. Together with my group, we are working at the implementation of a novel technology, that exploits the ferroelectric control of spin-charge conversion, what I presented was the development of a compact analytical model of the device.
ISAF conference is organized by IEEE and stands for International Symposium on Applications of Ferroelectrics. The research direction of my group has recently been approaching ferroelectricity and what we were bringing, though related to it, was slightly different from the majority of the topics explored there. I had the chance to learn about a lot of subjects and open questions I knew almost nothing about; on the other side I had to explain the basic concepts of spintronics to the people coming for the poster, which I believe has been a useful exercise.
Outside the stunning Da Vinci conference center, we met with some other scientists in a more informal environment and we could also appreciate the social life of a nice town like Tours.
One afternoon I had some time to play with the microscope during my school days. The moment I was out of sight of my teacher, I started looking at the things that I use every day. I still remember very vividly looking at a dead mosquito. Of course, I ate mosquitos every day ;).
Life have changed and now every afternoon I get to play with the microscope. Below you see a picture of my smartphone screen. On the top row is the picture as we see and in the bottom row is what I saw under the microscope. The matrix of red, blue, and green OLED (Organic Light Emitting Diode) lights up in different combinations and intensities to produce the 16 million colors that we see. We use it every day and technology has been around for a while now. But still to see it in action is very exciting.
These are some of the different types of devices I am working on now. They don´t look as beautiful as a mosquito. On the left we see a device with platinum contacts made with e-beam lithography with a 2D ferromagnet flake encapsulated with boron nitrite. On the right is another device with gold contacts in transverse and longitudinal geometries.
In the scope of ETH outreach week, my colleague Patrick and I showed high school students how thermal evaporation works. The idea of this week is to give high school students from Switzerland and abroad can get hands-on insights on different study programs, in our case materials science. We first introduced them to the general basics of thin films in general, absorption and different principles of film deposition.
In our case, a thermal evaporator was used to vaporise the source materials. Following, a sketch of the device is shown. It is an easy principle: in an evacuated volume, the material is heated inside a crucible until atoms and small cluster are evaporated. The vacuum is needed to prevent contamination of the film and to ensure the particles reach the substrate. At the substrate, the atoms and clusters condensate on the surface and form a film, just as any other surface inside the chamber.
Sketch of a typical thermal evaporator design
The students were allowed to carry out all steps by themselves under supervision. Firstly, the lab safety glasses had to be prepared and cleaned well. Then, they were placed inside the chamber, which was evacuated next. Now, the source materials were melted by resistive heating, while slowly increasing the power the evaporation rate was observed via an oscillating quartz crystal. After the desired rate was reached, the shutters were opened and the Poly(methyl methacrylate) (PMMA) glasses were coated.
The students were able to decide from different materials, where aluminium and copper have been the most common choices. Some tried some more interesting ideas, like making a bronze alloy from copper and tin. As explained in our introduction, absorption rates vary among the used materials. For example, 100 nm thick aluminium films will completely reflect the light while copper of the same thickness is still quite transparent.
PMMA glasses coated with a 120 nm thick bronze film.
Especially for sunglasses, it is important to have UV filters to protect the eyes. We made sure that materials we evaporated block most of UV light (below 350 nm wavelength) to have safe sunglasses. Anyway, since we did not deposit a sealing layer, our films are not scratch resistant. Therefore, our sunglasses are more meant to be a nice souvenir from their week at ETH Zürich.
It has been several months since I settled down in Zurich. I really enjoy the new start as a PhD student here at QZabre and Degen’s Group. People here are very nice and helpful, and willing to help me out when I get problems. Now I am occupied with the first project in my PhD life, i.e., to improve the spatial resolution of quantum sensor.
Quantum Sensing Magnetometer, QZabre AG
During the spare time, I’d like to explore the nature here in this country. Hiking around and breathing the fresh air, can always recharge me with maximum of energy so that I am able to dedicate myself back to the scientific work.
É Mé (on the top of Rigi)
Sometimes hiking brings me unexpected rewards. One huge stone engraved with Chinese characters ‘É Méi (峨眉, one of the most well-known mountain in China)’ on the top of Mountain Rigi is one of these unexpected rewards. You cannot imagine how excited and touched I was, when I saw thing possessing the same root and culture with me myself in a foreign country, especially as a ‘wanderer’ who has been away from home for more than two years.
It has been more than five months since I arrived in Halle. The time here defies any logic since every day is full of experiences, and I could say that I have been in Halle for over a year. But on the other hand, as we progress with the research and the constantly increasing learning curve, I could also say that I have been here less than a month. These very active first few months couldn’t have been possible without the beautiful vibe of Halle. A place where one can have an excellent week of work and a peaceful weekend at the park, perfect to start a whole new week full of new things to do and stories to write.
Ziegelwiese park, close to the river
Last month we had the first training session with almost every ESR, and it was incredible. Having the opportunity to share ideas and different perspectives about the topics and previous works is something I really think will make a difference in the program. The ethics and physics training sessions were incredibly useful and well presented. Besides, we had many interesting discussions arising from them, which I think might eventually result in very interesting collaborations. On top of everything, the city is beautiful, with many things to do and see, so combined with a perfect organization of the time and schedule, I was very impressed. Moreover, since I have to do my secondment in Grenoble, I cannot wait to come back and spend more time there, and I am looking forward to the next training session in Leuven!.
Before the trip to Grenoble, I started to study the orbital effect in a bilayer system with Rashba interaction. This project started as a practice of what I had learned in the first four months of my Ph.D. But once we saw the promising results, we were very excited about the model and the rich physics that we can extract from the calculations. At the moment, we are incorporating extensions that can be applied to this simple model so it can be more realistic. Luckily, in a few months, we will host the secondment of ESR1 (Eoin), and the timing will be perfect for us to discuss our simulations with their experiments and start a theoretical-experimental collaboration.
All and all, I think I couldn’t have asked for more or a better environment. Prost to Halle and the SPEAR program!!.
I started my PhD in September 2021 at the SPM group, University of Hamburg along with ESR 12 (Arturo). The past 7 months have been very interesting. So it was my first time in Germany and in the field of STM! It was a bit challenging (and is still is) to adapt to Hamburg due to it’s nature. I have never stayed in such a big city for a continuously long time ever before and so coming from small peaceful cities to a big and busy city requires patience to get adapted. But for sure, I am enjoying the place and exploring nearby places.
I have been working on a project that explores antiferromagnetism in atomic layered systems! It has been a lot of fun learning and seeing the magnetism in real space! Using an STM really allows us to see what we are doing as opposed to other transport measurements and imaging techniques! The group is very nice and closely packed (good bonding). The learning curve despite being very steep, feels so smooth and doable! I think I am very fortunate to have Kirsten as my supervisor! She makes difficult things look so easy! I always learn a lot from other group members about the amazing stuff they are doing in the field of skyrmions, superconductivity and Majorana fermions!
Cool lab!
When I have a long day at work, I usually go to the fantastic Elbphilaharmonie to have a scenic view of the harbour area. Another possibility is that I tunnel through the Elbe tunnel across the Elbe river to have another great view! And to find peace and nature, I keep visiting nearby areas like Lüneburg and Arhensburg! So if you are around, do not miss these places!
Me chilling at the Elbphilaharmonie (left) and me relaxing in the beautiful nature at Ahrensburg (right)
I am really excited for my new project and hope to unravel something that was never seen before! It has also been great to have good knowledge exchange with ESR 10 and ESR 13 about skyrmions! I am sure we are going to learn a lot in the coming months and definitely are looking forward to contribute to the understanding of skyrmions!
I arrived in Grenoble for the first time last year, in march, ready to start an internship in Spintec. In that moment, the town was nearly paralyzed for the restriction imposed by the pandemic. One year later, I was back in Grenoble. I started my PhD two month ago. I had the chance to meet again my colleagues, I fastly got updated on the progress that were made during my absence and picked up the work I left last september. The town I found had totally recovered from the long restrictions and, being winter, I could enjoy and take full advantage of the surroundings of Grenoble. For example, together with getting trained on new softwares and on the experimental equipment, I could also benefit of a nice introduction to skiing. Last month, we hosted in Grenoble the first Training for the SPEAR project. It was a surprising experience. It was a real pleasure to get to know in person the other guys participating to the projects. Both the the soft skills classrooms and the dinners contributed to create a nice synergy (or fellowhip, as someone mentioed). Moreover, we had the honor to assist to many inspiring lessons given by renowned scientists.
It is known by all that at the beginning of the world it was Thales of Miletus the one and First Lord of the Magnet. Over the thousands of years that followed him, many others searched for similar powers and honours trying to understand the Great Power of the Magnet, and from time to time, succeeding. Some of these heroes and their circumstances have been long ago forgotten, others persist in the millenary legends, such as Shen Kuo, Leonardo Garzoni, Hans Christian Orsted or Gauss among many others.
The title of Lord of the Magnet travelled through borders and was inherited for honours and achievements for tens of centuries, until the Shattering of the Unshattered occurred near a hundred years ago. The destruction of the Unshattered, the most basic piece of reality, plunged the world into chaos and instability. The pillars of reality crumbled under the heavy weight of a new, hostile and terrifying way of understanding nature. It was at that time when, for the first time in millennia, the title of the Lord of the Magnet was lost.
Not too long after the Shattering, remains of the Unshattered were found. Here we will not talk about these remains such as the Heart of Addition, or his sister, the Star of Subtraction. Not even about their guardian; the Neutral Peacekeeper, or other smaller pieces. Here we will talk about their essences. We will talk about their hearts, and about a part of them that defines what they are: here, we will talk about the Spin.
After the Shattering, with the disappearance of the Lord of the Magnet, thousands of false idols and corrupted prophets arose. Among them, some good men and women carried the remains of reality over their shoulders, and, with time and effort, unified the Spin as much as they could, for a future when a new Lord of the Magnet arrives. But times have changed, and maybe no more Lords of the Magnet will come, and maybe, no single person should ever bear this title again as there is no longer Magnet, but Spins.
And the remaining Spins have now been gathered, and they have been entrusted to us. And the ones who remember or dream about the great good times before the Shattering hope to see among us a new Lord of the Magnet. And we will not be that Lord, but we will wield its spirit together, like brothers and sisters, like a united hand where every finger plays its role for a greater good.
We will unshatter the Shattered. We will bring back the peace. We are the Fellowship of the Spins.
It has been seven months since I started my PhD studies in Leuven, a lovely, historic and energetic city.
Leuven is special. With over 600 years of history, old and beautiful buildings are spread all over the city. Wandering around the quaint roads and taking in the amazing views is the best way to release stress. In addition to its rich history and culture, institutions and universities like IMEC provide a brilliant environment for research. My host institution, IMEC, is a world-leading research and innovation hub in nanoelectronics and digital technologies. I’ll never forget how shocked I was when I first saw so many 300 mm wafers in the lab. Moreover, students from KU Leuven breathing life into the city, it’s incredible to see such a perfect combination between history and innovation.
As for the research, I will devote myself in developing SOT-MRAM, which is a promising candidate for next-generation MRAM. As a start to my studies, I have attended many training courses and with the enthusiastic help of my supervisors and colleagues, my studies are progressing very well. So far, I am really enjoying my life in this peaceful city and I hope I could taste all kinds of beers in this kingdom of beer.
It’s been almost five months now since I moved to San Sebastian, which is rather hard to believe. The city is known around Europe for its rich history, proud food culture, and incredible beaches. Having lived here for a few months now I can certainly see why this is the case. I’m doing my best to learn the language while I’m here, so that I can better appreciate the life here. This has been a really fun challenge, and I think I’m making good progress. Aside from the cultural aspect, the city is also home to a lot of cutting-edge research which I have been lucky enough to be a part of. Here at Nanogune some of the world’s leading work in Spintronics is being carried out. So far, Ive only really started to learn everything, from the theory to the practical techniques needed for this kind of science, so it’s a lot to take in. So far things are going well, and I’m looking forward to continuing my work here.
It has been several months since I have moved to Zurich, Switzerland, and in spite of few recent rainy and foggy winter days, I feel very well at home. Multiple reasons account for this: First of all, from my first few days I sensed the warm and kind atmosphere among my fellow PhD students and the whole research group lead by Prof. Pietro Gambardella. Whatever problem or scientific question I may have and occur during daily life, everybody likes to help and discuss all sorts of issues. This welcoming attitude greatly simplified my settling down process and enabled me during the last months to get accustomed to the measurement techniques to investigate magnetic tunnel junctions.
However, there is more to Zurich and Switzerland than only work: During the summer I exploited several days to enjoy the mountainous landscape by hiking and cycling. The first picture shows tired me during sunset after hiking up to Schilthorn summit, canton Bern, Switzerland.
One time, I cycled the Alps from Bodensee, Germany to Lago di Como, Italy. The Splügen pass, canton Graubünden, Switzerland is where we overcame the highest chain of mountains and is shown in the second picture. This crossing gave me a better feeling for the slighter and bigger variations in Swiss mentalities and lifestyles in different cantons – not to mention the differing but all great tastes of Swiss cheese.
Needless to say, but Zurich as the largest Swiss city does offer a plethora of opportunities to enjoy free time by itself: Bathing in the river (Limmat), having a barbecue at Zurich lake or walking the nearby hills, to enumerate only few.
Grenoble – Convergence of Science, Technology and Nature
It has been a few weeks since I started working at Antaios in Grenoble. Surrounded by the Chartreuse, the Vercors, and the Belledonne mountain chains, Grenoble serves as a gateway to the Alps. These mountain chains act as a directional reference for the people of Grenoble. For example, the doors to our office in Meylan are named after the mountain chains they face, Chartreuse and Belledonne.
Grenoble is a city full of adventure sports enthusiasts with activities ranging from hiking and rock climbing to skiing and snowboarding. I intend to take full advantage of these opportunities. One of the most common is the hike to the Fort de la Bastille. It is very easy to be enchanted by the bird’s eye view of the city from the top, especially during sunset or sunrise.
The rivers, Drac and Isére, add to the natural beauty of the city. Positioned at the convergence of these rivers lies the Polygone Scientifique which is home to many research laboratories like Spintec, Institut Néel, and European Synchrotron Radiation Facility (ESRF). I got a chance to visit Spintec and get a glimpse of these reputed research facilities.
Antaios feels more like a big family than a company to me. My colleagues introduced me to the French tradition of the Galette des Rois. Some of us bring a special cake, called the Galette des Rois, cut into multiple pieces. In one of the cake pieces is a small figurine. If you happen to have it in yours, you are declared the “King of the Day” and then it is your turn to get the Galette des Rois next.
Apart from such traditions, I am currently receiving training on different measurement techniques, simulation software, and design tools. It has been quite an interesting experience working with helpful and experienced colleagues. Everyday brings new knowledge and exciting challenges in the form of training and discussions. I look forward to working and learning with everyone at Antaios.
Hamburg exudes moisture and breathes fog. It flows, as a slippery snake sweating in silence among its canals. Hamburg embraces you with its omipresent humidity in an eternal, soft and vaporous hug. From time to time, Hamburg smiles shyly through a distant sun, and reminds you that it loves you (what Hamburg really does).
At weekends, at night, a new river, smaller and warmer than the Elbe, appears. A human surge coming from everywhere leads to its burning heart which is Reeperbahn. The wetness is forgotten, and the fog becomes steam born from the skin of an incommensurable inexhaustible crowd. The next morning, as if it were a beach full of stranded mermaids, the Fischmarkt gathers the ones who have survived the night.
Hamburg walks slowly side by side with you, but it walks ruthless. It never stops, and it encourages you to do the same, as if this millenary city believed in you even more than yourself.
Hamburg is my new home. I didn’t understand the city when I arrived in August, and I have not understood it yet, but I want to, and I will do it. Every day that I live in this great city I learn something new, I grow as a person, and I become more aware of the city, the culture, the world and myself. I love Hamburg, I love where I am and what I am. And this is just the beginning.
It’s been a little over a month since I arrived in Germany, and the first impressions are amazing. Halle is a beautiful town, with lots of green areas. We have a huge park near the campus where I can go for walks and enjoy nature.
I have had the warmest welcome, starting with a cake party thrown by my main advisor Dr. Mertig. Everyone in the group is really friendly and supportive, they have been assisting me in every single little problem. This certainly has been helpful as I navigate through a new country and language. Additionally, as part of my personal development and, of course, to get settled in Germany, I have enrolled myself in a German course provided by SPEAR and the University. This is a very fun and rewarding experience because I get to make a lot of friends from all over the world.
In the first month, I have also started my baby steps in this new field of research. I’m particularly happy to be developing project ESR10, Skyrmions have fascinating physics with promising applications. I have been learning tools that allow me to visualize these awesome spin textures and create simulations such as the one I made below of a Skyrmion in a racetrack memory. Hopefully in the next few months, I will be using these tools to uncover the physics and applications of Skyrmions.
My PhD started incredibly well! I had the luck of finding such a wonderful group of people always available for help and suggestions. I enjoyed a lot of time with them also outside the laboratory. It is common to organise something all together and Grenoble is famous for having beautiful mountains all around and a lot of people enjoying hiking. For this reason, only few days after I joined the group, we went all together to Le Col Vert.
Here we had lunch surrounded by nature and with a beatiful view of Grenoble’s surroundings.
About the everyday time on the lab: at the moment I am checking through the ST FMR technique to evaluate the charge to spin conversion of a topological insulator at different temperatures. The idea is to extract the efficiency of the conversion from the measurements, but this step is not straightforward. Everything is working well only thanks to the experienced members of my team, that they do not hesitate in helping and discussing the results. I spent also a lot of time in cleanroom to prepare the samples through depositions and etching. I am really happy in spending my time at work, since I am learning a lot of things and the experience is exciting everyday.
Two months have passed since the beginning of the research on using spintronics for ML hardware. Transfering a technology to an application regarding an already extremely complex system relying on an established industry is no joke, but here in IMEC the team is made up of people working at all levels of abstraction in conceiving electronic systems, and I learn a lot from the software as well as the hardware side to design Machine Learning algorithms. Learning as fast as possible is the key of my research at the moment. In the attempt of emulating the human brain with machines, lots of questions arise.
IMEC Tower. In my department most of the time is spent on designing and conceiving new circuits and architectures.
Indeed, the line of research in electronics has always been toward linearity, absence of noise and lowering the entropy of the system, giving us a sense of order which has brought us very far. However, the brain is still orders of magnitude better and more efficient than even the most advanced supercomputer, and we just know very little about it. This requires an effort to be more creative than ever.
On the other side, Leuven is a lovely, young city, full of events and parties in every corner of the city. I especially enjoy playing sports here as well as tasting one of the thousands of beer brands available in Belgium. The middle age gothic architecture is outstanding and it naturally reminds me of the stories of knights and people of the Western Europe, centuries ago.
In the last two weeks, thanks to an early part secondment, I had the opportunity to get to know many different preparation and exfoliation possibilities at CIC nanoGUNE. Besides the many scientific experiences, I came into contact with many friendly and helpful scientists and was able to enjoy the time there, also because of the good weather. Besides Marco, who works with me in Zurich, I also got to know two other ESRs personally here, Mayank and Eoin. Fortunately, my time in San Sebastián/Donostia coincided exactly with a statistically significant accumulation of birthdays, so I got to enjoy freshly baked cake at work surprisingly often.
The view over one of the beaches of San Sebastián/Donostia towards the city center.
I spent most of my time at the glove box exfoliating various non-stable materials and building stacks with the stamping system. In the picture you can see the transfer process, where the flakes are transferred to a substrate using polydimethylsiloxane (PDMS). With this technique, precisely aligned complex hetero structures can be produced successively.
Stamping process mid stamping. The exfoliated flakes are on the PDMS which is on the bottom side of the glass slide.
Back in Zurich, I will continue the exfoliation of van-der-Waals crystals of different materials. The new knowledge I gained at CIC nanoGUNE and especially the personal tips on the exfoliation for specific materials will help me to fabricate different types of samples in the near future, either in a controlled environment or under ambient conditions.
Finally, I can only thank you for the wonderful time and send my greetings to Spain.
Perhaps my ear to ear smile itself explains the joy I am experiencing in this moment. It was just two years ago when I was finishing my bachelor’s that I came across the word Spintronics. At that time, I did not realize that soon I would become a part of big project like SPEAR and that I would be working at CIC nanoGUNE (San Sebastián, Spain), where I would get to meet the creator of the Spintronics field itself, Noble laurate Prof. Albert Fert. Prof. Fert is a frequent collaborator of Prof. Felix Casanova, my supervisor and co-leader of the Nanodevices group, and he happened to be visiting our research center last month.
Although it has just been one month since I started my journey as a doctoral researcher at CIC nanoGUNE the experience has been very rewarding. I am learning new preparation and characterization techniques for the 2D magnetic materials which is exciting and challenging at the same time.
