SPICE Workshop on Quantum Functionalities of Nanomagnets, June 17th - 19th 2025
Markus Garst
Magnetic skyrmions are smooth textures of the magnetization that possess a non-trivial topology. Such classical textures are not exact groundstates of the quantum spin Hamiltonian and, consequently, they are in general affected by quantum fluctuations. We will provide an overview of current research on magnetic skyrmions in the quantum limit [1]. Various theoretical approaches have been applied to study quantum skyrmions, their properties and their ground states encompassing skyrmion crystal and skyrmion liquid phases. In particular, we discuss that the quantum dynamics of magnetic skyrmions is governed by a dipole conservation law associated with the topological charge, akin to that in fracton theories of excitations with constrained mobility [2]. As a result, an isolated skyrmion is intrinsically pinned to be immobile and cannot move at a constant velocity. Moreover, the topological charge density is shown to obey the Girvin-MacDonald-Platzman algebra that describes neutral excitation modes in the quantum Hall problem. This suggests that magnetic skyrmion materials offer a promising platform for exploring fractonic phenomena with close analogies to fractional quantum Hall states.
[1] A. Petrović, C. Psaroudaki, P. Fischer, M. Garst, C. Panagopoulos, arXiv:2410.11427[2] S Sorn, J Schmalian, M Garst, arXiv:2412.16284