Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - SORBET (Spin Orbitronics for Electronic Technologies)

Teaser

SORBET concerns the exploration of novel devices that rely on spin-orbitronics. SORBET especially focuses on Magnetic Racetrack Memory in which a seres of magnetic domain walls are moved to and fro along magnetic nanowires using nanosecond long current pulses to store digital...

Summary

SORBET concerns the exploration of novel devices that rely on spin-orbitronics. SORBET especially focuses on Magnetic Racetrack Memory in which a seres of magnetic domain walls are moved to and fro along magnetic nanowires using nanosecond long current pulses to store digital data. The objective is to create a non-volatile memory with up to one hundred times the storage capacity of the highest capacity charge based memories of today. To date the nanowire racetracks have been formed on flat surfaces but to enable the full potential of Racetrack Memory, the racetracks must be formed on vertical surfaces. A main objective of SORBET is to develop techniques to enable such 3D racetracks. Other objectives of SORBET include studying the underlying physics of the current induced domain wall motion to enable faster and more efficient domain wall motion. The speed of the domain walls determines the access time with which data encoded in domain walls can be read or written. Similarly, the lower the current density the less energy will be needed to operate Racetrack Memory. Another very important objective of SORBET is to explore alternatives to domain walls such as anti-skyrmions and to study new and novel methods to manipulating domain walls and anti-skrymions. These are tiny magnetic nano-objects that may be useful for Racetrack and other spin orbitronic technologies.

Work performed

\"We have developed substantial new capabilities for deposition of the atomically engineered magnetic multilayers structures needed for the magnetic racetracks.
We have made substantial progress in exploring the possibility of depositing these materials via atomic layer deposition which is needed to build \"\"vertical\"\" racetracks.
We have set up a Lorentz transmission electron microscope facility and have used this to discover, for the first time, anti-skyrmions in a tetragonal inverse Heusler compound. This work was published in Nature last year. We have shown that anti-skyrmions have distinct and useful properties compared to skyrmions which have previously been extensively explored.
We have shown the that the magnetic field- temperature phase diagram of anti-skyrmions is largely insensitive to the thickness of the lamella in which the anti-skyrmions are imaged compared to skyrmions. We have developed a model that can account for these distinct properties.
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Final results

Last year we discovered anti-skyrmions, a novel magnetic nano-object, that has unique properties. We have demonstrated that we can tune the size of the anti-skyrmions from a few tens of nanometers t microns in the same material, which was not anticipated by any theoretical model.
We discovered unexpectedly that chiral domain walls move at different speeds under current pulses in racetracks that are curved and that alternate domain walls move at different speeds. However, we discovered that in synthetic antiferromagnetic racetracks all the domain walls move at the same speed. We developed an analytical model to account for these properties.