Field direction dependent skyrmion crystals in noncentrosymmetric cubic magnets: A comparison between the point groups (O,T) and T d

Abstract

We investigate the instability toward a skyrmion crystal (SkX) in noncentrosymmetric cubic magnets with an emphasis on a comparison between point groups (O,T) and Td. By constructing low-temperature magnetic phase diagrams under an external magnetic field for three directions based on numerically simulated annealing, we find that the system under the point groups (O,T) exhibits different two types of SkXs depending on the field direction, while that under Td does not show such an instability. The difference between them is understood from the difference in the momentum-dependent Dzyaloshinskii-Moriya interaction under each point group. Meanwhile, we show that the system under Td leads to the SkX instability by considering an additional effect of the uniaxial strain, which lowers the symmetry to D2d. We obtain two different SkXs: Néel-type SkX and anti-type SkX, the former of which is stabilized in the presence of the interactions at the three-dimensional ordering wave vectors. The present results provide rich topological spin textures in the three-dimensional systems, which are sensitive to the magnetic-field direction and point-group symmetry.