We study the emergence of spontaneous skyrmion lattices in an Fe monolayer in fcc and hcp stacking on the Ir(111) surface using density functional theory (DFT). For fcc-Fe/Ir(111) we find the well-known square nanoskyrmion lattice. However, for hcp-Fe/Ir(111) the hexagonal skyrmion lattice previously proposed based on experiments is energetically unfavorable with respect to a hexagonal multi-Q state with nearly collinear magnetic moments. By mapping our DFT calculations to an atomistic spin model we demonstrate that the interplay of pair-wise exchange, higher-order exchange, and Dzyaloshinskii-Moriya interaction is decisive for the symmetry and collinearity of the obtained spin lattice.
@article{arxiv.2301.13851,
title = {Spontaneous square vs. hexagonal nanoscale skyrmion lattices in Fe/Ir(111)},
author = {Mara Gutzeit and Tim Drevelow and Moritz A. Goerzen and Soumyajyoti Haldar and Stefan Heinze},
journal= {arXiv preprint arXiv:2301.13851},
year = {2023}
}