Condensed Matter Theory Seminar | October 18, 14:30

Nonequilibrium Quantum Dynamics of Magnetic Skyrmions

Christina Psadouraki

We study the quantum propagation of a skyrmion in chiral magnetic insulators by generalizing the micromagnetic equations of motion. The fluctuations around the skyrmionic configuration give rise to a damping derived microscopically, which in some limit reduces to a skyrmion mass. We demonstrate that a skyrmion in a confined geometry behaves as a massive particle, a discovery with great impact on the technologically important case of linear tracks relevant for magnetic memory devices. In the presence of time-dependent oscillating magnetic field gradients, the unavoidable coupling of the external field to the magnons gives rise to time-dependent dissipation for the skyrmion, with measurable consequences on the skyrmion path. These ac fields act as a net driving force on the skyrmion via its own intrinsic magnetic excitations. We generalize the standard quantum theory of dissipation to include the stochastic effects of the driven bath on the skyrmion dynamics. Our work initiates studies towards the possibility of observing a quantum mechanical behavior at a mesoscopic scale. I will briefly talk about the observability of tunneling events, in particular quantum depinning of a magnetic skyrmion out of a pinning center.


University of Cologne
Seminar Room 0.03, ETP
Contact: Alex Altland