Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 21: Correlated Electrons: Poster Session

TT 21.36: Poster

Mittwoch, 7. September 2022, 15:00–18:00, P1

Driven magnets: Domain wall motion in ferrimagnets in an oscillating magnetic field — •Dennis Hardt and Achim Rosch — Institute for Theoretical Physics, University of Cologne, Germany

Transition regions between two magnetic domains are described by domain walls (DWs).

In this work, we numerically study a 1D ferrimagnet with anisotropy term given by a symmetric double-well potential in magnetization in z-direction. This establishes a Goldstone mode as rotation in the x-y-plane which can be activated by driving the system with an oscillating magnetic field in z-direction.

At T=0 (noise-free case) this leads to a spontaneous symmetry breaking visible in the collective movement of all DWs in one direction (left or right). We also found an analytical description for this limit.

At finite temperature, DW-pairs can also be created meaning that there is a competition between the annihilation (2 DWs meet due to diffusion and driving) and the creation (due to noise).

The noise-created domain walls are driven randomly in left or right direction. This leads to a suppression of the total number of DWs compared to the non-driven thermal case.