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PGI-1 Talk: Dr. Mikhail Titov

Anisotropy induced by spin-orbit interactions: new insights to chiral magnetism and magnetization dynamics

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31 Jul 2019 11:30
venue
PGI lecture hall

Radboud Uni., Nijmegen, Netherlands

Abstract:

In this talk I overview our recent progress in understanding the role of strong spin-orbit interactions of conduction electrons in magnetic systems. First, I present a general point group classification of linear-in-gradient terms in micromagnetic energy that is designed to revise the seminal work of Bogdanov and Yablonskii. In particular, I will demonstrate that, apart from Dzyaloshinskii-Moria interactions represented by Lifshitz invariants (LI), there exists non-LI contributions in micromagnetic energy. Such contributions are shown to be highly relevant unless the spin-orbit coupling is vanishingly small as compared to an effective s-d exchange. Such non-LI terms lead to the splitting of magnon bands that can be observed in optical experiments and may help stabilizing chiral magnetic structures. I will also demonstrate that in crystals defined by the point groups Td, Dh3, and Ch3, the non-LI terms are the only linear-in-gradient terms in micromagnetic energy. I will illustrate the general classification with analytical results for a generalized Rashba ferromagnet in two dimensions.

In the second part of my talk, I present a detailed study of current induced phenomena in a Rashba ferromagnet. In particular I will show how Gilbert damping and in-plane spin-transfer torques acquire strong anisotropy due to spin-orbit interaction. I will also derive a general relation between these quantities that make the speed of magnetic textures universally equal to the drift velocity of conduction electrons in the Rashba model. At the end of my talk I will compare our microscopic results to the standard phenomenological equations on magnetization dynamics to make some further insights.

Contact

Prof. Dr. Yuriy Mokrousov
Phone: +49 2461 61-4434
email: y.mokrousov@fz-juelich.de

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