TY - JOUR

T1 - Thermodynamically stable skyrmion lattice in a tetragonal frustrated antiferromagnet with dipolar interaction

AU - Utesov, Oleg I.

N1 - Funding Information: I am grateful to V. A. Ukleev and A. V. Syromyatnikov for valuable discussions. The reported study was supported by the Foundation for the Advancement of Theoretical Physics and Mathematics “BASIS.” Publisher Copyright: © 2021 American Physical Society. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/2/8

Y1 - 2021/2/8

N2 - Motivated by recent experimental results for GdRu2Si2 [Khanh, Nat. Nanotechnol. 15, 444 (2020)10.1038/s41565-020-0684-7], in which a nanometric square skyrmion lattice was observed, we propose a simple analytical mean-field description of the high-temperature part of the phase diagram of centrosymmetric tetragonal frustrated antiferromagnets with dipolar interaction in the external magnetic field. Dipolar forces provide momentum-dependent biaxial anisotropy in reciprocal space. It is shown that in a tetragonal lattice, in the large part of the Brillouin zone, for mutually perpendicular modulation vectors in the ab plane this anisotropy has mutually perpendicular easy axes and collinear middle axes, which leads to double-Q modulated spin structure stabilization. In the large part of its stability region, the latter turns out to be a square skyrmion lattice with a topological charge of ±1 per magnetic unit cell, which is determined by the frustrated exchange coupling and thus nanometer sized. Easy and middle axes can be swapped in the presence of additional single-ion easy-axis anisotropy. This results in the different phase diagram. It is argued that the latter case is relevant to GdRu2Si2.

AB - Motivated by recent experimental results for GdRu2Si2 [Khanh, Nat. Nanotechnol. 15, 444 (2020)10.1038/s41565-020-0684-7], in which a nanometric square skyrmion lattice was observed, we propose a simple analytical mean-field description of the high-temperature part of the phase diagram of centrosymmetric tetragonal frustrated antiferromagnets with dipolar interaction in the external magnetic field. Dipolar forces provide momentum-dependent biaxial anisotropy in reciprocal space. It is shown that in a tetragonal lattice, in the large part of the Brillouin zone, for mutually perpendicular modulation vectors in the ab plane this anisotropy has mutually perpendicular easy axes and collinear middle axes, which leads to double-Q modulated spin structure stabilization. In the large part of its stability region, the latter turns out to be a square skyrmion lattice with a topological charge of ±1 per magnetic unit cell, which is determined by the frustrated exchange coupling and thus nanometer sized. Easy and middle axes can be swapped in the presence of additional single-ion easy-axis anisotropy. This results in the different phase diagram. It is argued that the latter case is relevant to GdRu2Si2.

UR - http://www.scopus.com/inward/record.url?scp=85100638065&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.103.064414

DO - 10.1103/PhysRevB.103.064414

M3 - Article

AN - SCOPUS:85100638065

VL - 103

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 6

M1 - 064414

ER -