Stability of skyrmion crystal phase in antiferromagnetic triangular lattice with DMI and single-ion anisotropy

TL;DR

This study explores the stability of skyrmion crystal phases in a frustrated antiferromagnetic triangular lattice with Dzyaloshinskii-Moriya interaction and single-ion anisotropy, revealing conditions for their stabilization.

Contribution

It provides phase diagrams showing the stability regions of skyrmion lattice phases considering DMI, anisotropy, temperature, and magnetic field, using Monte Carlo simulations.

Findings

Skyrmion lattice phase is stabilized at certain temperature and field ranges for large DMI.

Easy-plane anisotropy extends the skyrmion stability window at lower fields.

Skyrmions persist at low temperatures with small DMI and easy-plane anisotropy.

Abstract

We study a frustrated antiferromagnetic Heisenberg model on a triangular lattice with the Dzyaloshinskii-Moriya interaction (DMI) in the presence of an external magnetic field and a single-ion anisotropy. Phase diagrams in the temperature-field plane for both easy-axis and easy-plane anisotropy of a varying strength are constructed in the regimes of a moderate and strong DMI by parallel tempering Monte Carlo simulations. For the considered range of parameters the phase diagrams featuring up to four ordered phases are identified. A skyrmion lattice (SkX) phase is found to be stabilized within some temperature and field window for sufficiently large DMI and not too strong anisotropy. For the systems with moderate (larger) DMI, a small easy-plane (easy-axis) anisotropy is concluded to be beneficial by extending (shifting) the field window of the SkX appearance to lower values. The Metropolis dynamics is employed to probe the persistence of SkX upon quenching the field to zero or small finite values. The most favorable conditions for the skyrmions persistence are confirmed at low temperatures, small DMI and small easy-plane anisotropy values.