Entrada Departamento Notícias Seminário - Skyrmionics with ferromagnets and antiferromagnets

Seminário - Skyrmionics with ferromagnets and antiferromagnets

Oleg Tretiakov

Institute for Materials Research, Tohoku University, Sendai, Japan

1 de junho, 14:30, auditório -1.17


Skyrmions are topologically protected spin textures, which can be used in spintronic devices for information storage and processing. Ferromagnetic skyrmions attracted a lot of attention because they are small in size, better than domain walls at avoiding pinning sites, and can be moved very fast by electric current in ferromagnet/heavy-metal bilayers due to novel spin-orbit torques. I will formulate the microscopic theory of these torques in the presence of disorder and calculate the skyrmion Hall angle, which was recently revealed by X-ray microscopy. We show that this angle depends on dynamical deformations of the skyrmion due to spin-orbit torques.

Meanwhile, the ferromagnetic skyrmions also have certain disadvantages to employ them in spintronic devices, such as the presence of stray fields and transverse to current dynamics. To avoid these unwanted effects, we propose a novel topological object: the antiferromagnetic skyrmion. This topological texture has no stray fields and its dynamics are faster compared to its ferromagnetic analogue. More importantly, I will show that due to unusual topology it experiences no skyrmion Hall effect, and thus is a better candidate for spintronic applications. Furthermore, I will discuss the lifetimes of both antiferromagnetic and ferromagnetic skyrmions at finite temperatures. Lastly, I will talk about antiskyrmions – anisotropic topological objects, which were recently observed in systems with anisotropic Dzyaloshinskii-Moriya interaction. I will explain their dynamics in ferromagnets and make their prediction in antiferromagnets.

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