Face centered cubic and hexagonal close packed skyrmion crystals in centro-symmetric magnets

TL;DR

This paper demonstrates the formation of face centered cubic and hexagonal close packed skyrmion crystals in layered centrosymmetric magnets through simulations, revealing new stacking arrangements and particle-like behavior of pancake skyrmions.

Contribution

It introduces novel stacking configurations of skyrmion crystals in layered magnets and analyzes their dynamics, expanding understanding of skyrmion arrangements beyond traditional triangular lattices.

Findings

Face centered cubic and hexagonal close packed skyrmion crystals identified

Inter-layer exchange controls skyrmion stacking arrangements

Pancake skyrmions exhibit particle-like sliding motion under current

Abstract

Skyrmions are disk-like objects that typically form triangular crystals in two dimensional systems. This situation is analogous to the so-called "pancake vortices" of quasi-two dimensional superconductors. The way in which skyrmion disks or pancake skyrmions pile up in layered centro-symmetric materials is dictated by the inter-layer exchange. Unbiased Monte Carlo simulations and simple stabilization arguments reveal face centered cubic and hexagonal close packed skyrmion crystals for different choices of the inter-layer exchange, in addition to the conventional triangular crystal of skyrmion lines. Moreover, an inhomogeneous current induces sliding motion of pancake skyrmions, indicating that they behave as effective mesoscale particles.