Unconventional topological spin textures in spintronics

This thesis focuses on the study of unconventional topological spin textures present in antiferromagnetic thin film materials.

In the field of spintronics, spin correlations have attracted considerable attention, facilitating progress in fundamental physics and the development of new applications. Some effects, such as the topological Hall effect, are related to the specific local arrangement of magnetic moments, and only a few materials exhibit them. This is the case of antiferromagnets and more particularly of spintronic effects due to the presence of skyrmions in antiferromagnets. As they have no net magnetization, the nucleation of antiferromagnetic skyrmions is however difficult and remains the bottleneck to overcome to benefit from all their advantages.

The challenge of this thesis is to understand and predict, through simulation, how to nucleate, stabilize, then excite and detect skyrmions in antiferromagnetic thin films, thanks to their own spintronic effects, and then to demonstrate the proof of concept experimentally, through the realization of magnetic stacks and ad hoc experiments.

One of the particularities of the proposed project, which combines simulations and experiments, lies in

1. the preliminary choice of the method for nucleating skyrmions in the antiferromagnet, which consists of printing the textures of a ferromagnet

2. the choice of atomistic simulation in direct link with the developers of one of the most powerful simulation codes in this field

3. a privileged experimental environment for theory-experiment exchanges in order to mutually test ideas and results.

This project responds to the need for new knowledge and new models to better understand the new topological phases and their associated effects. Such a study is also an essential prerequisite for the development of new components compatible with spintronic devices, since its ambition is to overcome the main bottleneck to benefit from the many advantages of antiferromagnetic skyrmions.

SPINTEC is a strong player in both ferromagnetic skyrmions and antiferromagnetic spintronics, at the crossroads of which this subject is situated. This work will build on preliminary experimental and simulation results obtained between SPINTEC and YORK in the UK, which are experts in atomistic simulations.

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