Voltage controlled operation and mutual synchronization of MTJ-based spin Hall nano-oscillator chains and arrays for neuromorphic computing

Host institution

NanOsc is a Swedish R&D SME, developing Spin torque nano-oscillators (STNOs) and spin Hall nano-oscillators (SHNOs) for use at very high frequencies (10-100 GHz), primarily within the fields of space communication, high speed radio links, vehicle radar applications, intra/inter-chip communication, and neuromorphic computing. NanOsc’s expertise comprises the fabrication, characterization, optimization and reliability of the physical STNO and SHNO core devices. Since its foundation in 2006, NanOsc’s business is to develop intellectual property on STNOs and SHNOs, design instruments for their characterization, and with partners develop novel applications on these technologies. NanOsc benefits from close ties with the University of Gothenburg where it is one of the major external users of the MC2 cleanroom.

The project will be carried out in the laboratory of Prof. Johan Åkerman at University of Gothenburg.

Supervisor

Prof. Johan Åkerman

Description

The project will study nano-constriction SHNOs based on W/CoFeB/MgO stacks with and without voltage control and with and without magnetic tunnel junctions (MTJs). NanOsc has recently demonstrated mutual synchronization in both chains and two-dimensional arrays of Pt/NiFe-based SHNOs as well as voltage-controlled operation of W/CoFeB/MgO-based SHNOs. In this project, the candidate will investigate mutual synchronization in long chains and large arrays of such W/CoFeB/MgO-based SHNOs and, in particular, study whether voltage control can be used to control their mutually synchronized state. The possibilities for carrying out neuromorphic computing using such voltage controlled SHNO arrays will be explored. Their functionality with respect to thickness, composition, and perpendicular magnetic anisotropy of the CoFeB layer as well as nano-constriction width, shape, and separation will be mapped out. Non-volatile memristive control of SHNOs through the use of charge trapping inside the dielectric gate controlling the SHNO will also be attempted. Such an approach will enable the storage of local weights that can be used to train the oscillator array to match certain input patterns. The candidate will work with a large international group of excellent graduate students, postdocs, and more senior scientists, as well as the NanOsc engineers in charge of transferring these results to commercial applications.

Requirements

  • Master’s degree in Physicsor a similar field
  • Good verbal and written communication skills in English.

Although not compulsory, the following points will be considered:

  • Previous knowledge of spintronics.
  • Experience in the following techniques: thin film growth, nanofabrication, magneto-transport, microwaves, micromagnetic simulations
  • Self-motivation and willingness to perform independent research.

Planned Secondments

CEA (Grenoble, France), under the supervision of Jean-Philippe Attané.

IMEC (Leuven, Belgium), under the supervision of Sebastien Couet.

Registering University

UGOT (Gothenburg, Sweden).


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