Quantum fluctuations in the order parameter of quantum skyrmion crystals

Abstract

Traditionally, skyrmions are treated as continuum magnetic textures of classical spins with a well-defined topological skyrmion number. Owing to their topological protection, skyrmions have attracted great interest as building blocks in future memory technology. Smaller skyrmions offer greater memory density; however, quantum effects are not negligible for skyrmions with sizes of just a few lattice constants. In this paper we study quantum fluctuations around dense skyrmion crystal ground states, and focus on the utility of a discretized order parameter for quantum skyrmions. The order parameter is found to be a useful indicator of the existence of quantum skyrmions, and captures the quantum phase transition between two distinct skyrmion phases.