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arXiv · 2402.11721

Double-$Q$ and quadruple-$Q$ instabilities at low-symmetric ordering wave vectors under tetragonal symmetry

Satoru Hayami
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Abstract

Multiple-$Q$ states are expressed as a superposition of spin density waves at multiple ordering wave vectors, which results in unconventional complicated spin textures, such as skyrmion, hedgehog, and vortex. We investigate the multiple-$Q$ instability by focusing on the low-symmetric ordering wave vectors in momentum space. By systematically performing the simulated annealing for effective spin models with various ordering wave vectors on a two-dimensional square lattice, we classify the magnetic phase diagram into four types according to the position of the ordering wave vectors. Three out of four cases lead to a plethora of isotropic multiple-$Q$ instabilities yielding collinear, coplanar, and noncoplanar double-$Q$ and quadruple-$Q$ magnetic phases, while the remaining case leads to an anisotropic double-$Q$ instability when the multiple-spin interaction is introduced. Our results indicate that exotic multiple-$Q$ phases distinct from the skyrmion crystal phase are expected when the ordering wave vectors lie on the low-symmetric positions in the Brillouin zone.

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Satoru Hayami. 2024-02-18. Double-$Q$ and quadruple-$Q$ instabilities at low-symmetric ordering wave vectors under tetragonal symmetry. https://doi.org/10.1103/physrevb.110.014404

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