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MA: Fachverband Magnetismus

MA 12: Magnetization Dynamics and Damping

MA 12.7: Vortrag

Dienstag, 18. März 2025, 11:00–11:15, H19

Landau-Lifshitz damping from Lindbladian dissipation in quantum magnets — •Götz Uhrig — TU Dortmund University

As of now, the phenomenological classical Landau-Lifshitz (LL) damping of magnetic order is not linked to the established quantum theory of dissipation based on the Lindbladian master equation. This is an unsatisfactory conceptual caveat for the booming research on magnetic dynamics. Here, it is shown that LL dynamics can be systematically derived from Lindbladian dynamics using a local mean-field theory. Thereby, the successful LL approach is set on a firm quantum basis in the regime where the Lindblad approach is applicable. Furthermore, we extend the LL dynamics in a systematically controlled way to include not only changes of the orientation of the magnetization m^→, but also of its length |m^→|. The key aspect is that the Lindbladian relaxation must be adapted to the Hamiltonian H(t) at each instant of time in time-dependent non-equilibrium systems. It is conjectured that this idea holds true well beyond the damping of magnetic dynamics given the appropriate hierarchy of time scales.

Keywords: Lindblad dissipation; Landau-Lifshitz relaxation; quantum master equation; Gilbert damping; magnetic relaxation