Stabilization of skyrmion textures by uniaxial distortions in noncentrosymmetric cubic helimagnets

In cubic noncentrosymmetric ferromagnets, uniaxial distortions suppress the helical states and stabilize skyrmion lattices in a broad range of thermodynamical parameters. Using a phenomenological theory for modulated and localized states in chiral magnets, the equilibrium parameters of the skyrmion and helical states are derived as functions of the applied magnetic field and induced uniaxial anisotropy. These results show that due to a combined effect of induced uniaxial anisotropy and an applied magnetic field, skyrmion lattices can be formed as thermodynamically stable states in large intervals of magnetic field and temperatures in cubic helimagnets, e.g., in intermetallic compounds MnSi, FeGe, (Fe,Co)Si. We argue that this mechanism is responsible for the formation of skyrmion states recently observed in thin layers of ${\text{Fe}}_{0.5}{\text{Co}}_{0.5}\text{Si}$ [X. Z. Yu et al., Nature (London) 465, 901 (2010)].