Author: Ismael Ribeiro

Can we emulate the brain?

Have you ever wondered how your brain effortlessly recognizes faces, understands language, makes quick decisions, or learns from past experiences? These seemingly simple tasks pose significant challenges for conventional computers, which consume considerable energy handling precise numerical calculations step-by-step. The brain’s remarkable efficiency arises from its ability to perform numerous parallel computations simultaneously, often with lower precision. This observation raises an intriguing question: Can artificial systems replicate the brain’s impressive efficiency?

Neuromorphic computing tackles exactly this challenge. This emerging technology aims to mimic the brain’s structure and function, specifically its essential components—neurons and synapses. Neurons are tiny processing units interconnected by synapses that transmit electrical signals known as spikes. Remarkably, the human brain accomplishes all these tasks while consuming only about 20 watts of energy—comparable to a dim light bulb—demonstrating exceptional efficiency. By replicating these biological interactions, neuromorphic computing promises substantial improvements in computational power and energy efficiency, potentially leading to powerful yet sustainable solutions.

One promising technology for neuromorphic computing is spintronics, which utilizes the magnetic spins of electrons to build innovative devices. There are several ways to use spintronic devices for neuromorphic computing. I will talk about my favorite: magnetic skyrmions! Imagine a skyrmion as a tiny magnetic vortex, where electron spins align into stable, swirling patterns resembling miniature whirlpools or galaxies, but in a magnetic material. This intricate configuration gives skyrmions remarkable stability, allowing them to be reliably manipulated by electrical currents at nanoscale dimensions (see figure for a visual example).

Biological neurons can be effectively modeled using RC circuits—basic electronic components combining resistance (R) and capacitance (C) to control electrical signals. These circuits capture the essential dynamics of neurons through the Leaky-Integrate-Fire (LIF) model, which is widely adopted in neuroscience to describe neuron behavior. Remarkably, skyrmions can replicate these neuronal dynamics at a nanoscale. By placing a skyrmion within a specially engineered magnetic environment where the perpendicular magnetic anisotropy (PMA)—which defines how strongly spins prefer aligning perpendicular to the surface—varies quadratically, the skyrmion moves predictably under electrical stimulation. The applied current induces a force that competes with the force due to the gradient, causing the skyrmion to shift its position, similar to how voltage accumulates in a capacitor during charging. Once the current ceases, the skyrmion naturally returns to its original position, effectively simulating the discharge phase of a capacitor. This motion directly mirrors the LIF neuron’s behavior, which shows that skyrmions have the potential to efficiently emulate biological neuron dynamics.


Scaling these skyrmion-based neuromorphic devices involves overcoming challenges in precise fabrication, maintaining stability, and integrating them into existing technologies. Despite these challenges, skyrmions might have a crucial role in neuromorphic computing. So, can we emulate the brain? Well, at least NOT YET :((. However, scientists have been able to emulate individual neurons with skyrmions (and other spintronic devices). Given that the brain consists of billions upon billions of interconnected neurons, I guess we could say, “Let’s take one neuron at a time… one neuron at a time.”

The end of my PhD’s (net)work

The summer has passed, and the leaves have turned orange; some have even started to fall. For me, this marks the end of my PhD’s (net)work. Since July, I’ve been on the move with business trips, conference presentations, and, of course, a bit of the usual summer vacation. It’s been a packed few months with a lot of great memories. I got to present my work, win an art contest at the ICM conference in Italy with the image below, and even got officially engaged (long story here) in Rome!

During my secondment, I spent time in the beautiful city of San Sebastián, where I enjoyed pintxos, the beach, and the beautiful hikes. In the middle of all this, I also organized a retreat for the International Max Planck Research School (IMPRS), which I am part of at the Max Planck Institute in Germany. Much of the inspiration for planning this retreat came from my experience at a summer school organized by ESR 3, Marco, back in 2022 in Lausanne, Switzerland. That summer school remains the best conference/school I’ve ever attended—it truly influenced my research interests and shaped the direction of my PhD. Below is a picture of one of the round tables from our retreat, inspired by the ones in Marco’s school. Here, I’m discussing creativity in science with Dr. Stuart Parkin (the mind behind racetrack memory, a core concept in my SPEAR project), Dr. Hyunsoo Yang, and Dr. Amir Capua.

In between all these trips, there was still plenty of work to do. I wrote my final PhD paper, which I’m currently in the process of submitting. This work has been a long time in the making and will be the core of my PhD thesis. With this final paper, I finally managed to bridge my research on skyrmions with neuroscience. It’s taken everything I’ve learned from my previous papers to understand the conditions that can make a skyrmion truly behave like an artificial neuron—something I’ve been pursuing for a long time.

Now, as I reach the end of my time with the SPEAR network project, I can’t help but feel like I’m closing one of the most meaningful and exciting chapters of my life. I have to give a special thanks to the person who helped make this project a success: our coordinator, Eli. Beyond her patience with my delayed reports (sorry, Eli!), she’s just an incredible person who has been a true pillar in this journey. I also want to thank Sofia for her role in our soft skills training. Her empathy and kindness in working with a bunch of skeptical physicists was something to admire, and I genuinely believe her guidance has made me a better presenter and scientist.

Finally, a big thank you to all the ESRs! It was a joy getting to know each of you, and I wish you all the best in your future endeavors. This project aimed to build a network of researchers, and I have to admit that I initially underestimated the power of networking in science. But looking back on my PhD journey, I can see the impact clearly. The connections and exchanges I was exposed to through the SPEAR project have shaped my research, my future, and who I am. Simply put, thank you all!

Happy New Year

Wow, what a year 2023 has been! It feels like that was just a week ago when I likened my life to a farming game in a blog [link to blog]. I’ve ‘harvested’ my efforts, as you can see in my recent paper [link to paper] and the picture I use to advertise this work below.

However, here it is – the final year of our ITN is upon us. As 2023 comes to a close, I find myself in a contemplative and somewhat melancholic state, reflecting on the past year’s journey. It’s been an incredible year, filled with treasured moments, as you can see in the collages below, showcasing snapshots from 2023 with the other ESRs and our ITN. Looking ahead to 2024, my wish is simple: for nothing to change. Yet, I know this is unlikely since our ITN will end, and I have to submit my PhD thesis and move on.

If you ever spend New Year in Brazil, you will notice a unique tradition: nearly everyone wears white. This tradition comes from a belief that the color of your clothes at midnight symbolizes your hopes for the new year. White, chosen by about 99% of people, signifies a wish for peace. Other colors represent different wishes – red for love, yellow for happiness, green for health, and so on. The specific meanings can vary, but the majority opt for white. As for me, known for usually wearing black, I’m not the Brazilian Johnny Cash, and it’s not an intentional statement. But during the New Year, I feel an urge to wear white, conforming to the local custom. Whether the colors we wear at midnight have any real effect, I can’t say – I don’t think so.

As far I know, there’s no meaning if you wear black – except that you are the gothic/emo teenager of your family. It may be time for me to start a new tradition. Wearing black on New Year’s Eve would bring a year where things stay just as they are. This would really come in handy; after all, I wore black last New Year’s Eve.

The Ph.D. game

When I was a kid, one of my favorite games was Harvest Moon (the picture below). In this game, you inherit a farm and have three years (in-game time) to expand it, or the village’s mayor will take your farm back. In the game, you must collaborate with funny characters living in the town to build tools, buy animals, sell your harvest, etc. I have always liked it because most of the days, you don’t really do anything differently; you wake up, water your plants, collect the eggs, sheepshearing, milk the cows… – rinse and repeat. Always working on the larger goal of expanding the farm as time passes. Well, my current Ph.D. life weirdly parallels this game, and it’s actually kind of amusing.



This is how my days now echo the in-game routine: I rise with the sun, but instead of tending to crops, I dive headfirst into my calculations from where I left off. Carefully adding more terms in my Taylor expansions so that my equations grow slowly but steadily. Instead of collecting eggs, I am collecting data with my simulations with skyrmions. I am “codeshearing” every day. I have to “trim” my codes so they don’t grow wild and ugly. Instead of extracting milk from virtual cows, I am working patiently to extract valuable insights and solutions from all these data. As the cows in the game would moo-ve my farm toward prosperity, I hope these insights will moo-ve my research toward a published paper. And most importantly, just like I have three years to build up the farm, I also have three years to build up all this learning into a Ph.D. thesis.

The Ph.D. sure ain’t a walk in the park. It takes a lot of patience and incremental work. But just like I have so much fun doing the same thing in a game toward a larger goal, I am having fun with my Ph.D. I’m curious if my background in Brazil’s countryside is why I like this game so much! So here’s to more days of ‘farming’ data and mathematical equations while making the most of this unique Ph.D. journey!

Talk to people

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).

First impressions and First steps

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.

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