Double-<i>Q</i> Instability in Noncentrosymmetric Tetragonal Magnets with Bond-Dependent Magnetic Anisotropy Under an In-Plane Magnetic Field

Abstract

We investigate the instability toward a double-Q state, which consists of a superposition of two spin density waves at different wave vectors, on a two-dimensional noncentrosymmetric square lattice in an in-plane external magnetic field. By performing the simulated annealing for the spin model with the Dzyaloshinskii–Moriya interaction and bond-dependent anisotropic interaction, we obtain four types of double-Q states depending on the sign of the bond-dependent anisotropic interaction. On the other hand, only the single-Q spiral state appears in the absence of the bond-dependent anisotropic interaction. The present results suggest that the interplay between the Dzyaloshinskii–Moriya interaction and bond-dependent anisotropic interaction can give rise to multiple-Q states for both zero and nonzero in-plane magnetic fields.

Keywords

• multiple-Q state
• Dzyaloshinskii–Moriya interaction
• magnetic field
• square lattice
• bond-dependent magnetic anisotropy