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Exciting skyrmions in chiral magnets

Markus Garst, Universität zu Köln

15.07.2014 at 11:00 

Chiral magnets, encompassing the metal MnSi, the semiconductor Fe1-xCoxSi and the insulator Cu2OSeO3, gain Dzyaloshinskii-Moriya spin-orbit energy by twisting the magnetization on a long length scale resulting in spatially modulated magnetic skyrmion textures. The topological nature of these objects gives rise to various interesting phenomena like a topological Hall effect, a Skyrmion-flow Hall effect and spin-torque effects at ultralow threshold currents. This presentation focusses on the excitations of magnetic skyrmions and their interaction with spin-waves. After a short discussion of the magnetic resonances within the skyrmion lattice phase [1], we theoretically explore the excitation modes of a single skyrmion and its magnon scattering cross section. Due to the skyrmion topology, the magnons are skew scattered which leads to a magnon Hall effect. The magnons also transfer momentum to the skyrmion, and we discuss the resulting effective Thiele equation of motion [2]. Our results provide, in particular, the basis for a theory of skyrmion caloritronics for a dilute skyrmion gas in clean insulating chiral magnets.

[1] T. Schwarze, J. Waizner, M. Garst, A. Bauer, I. Stasinopoulos, H. Berger, C. Pfleiderer and D. Grundler, submitted to Nature Materials.
[2] C. Schütte and M. Garst, submitted to Phys. Rev. B. [arXiv:1405.1568]

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