Vital role of magnetocrystalline anisotropy in cubic chiral skyrmion hosts

Magnetic anisotropy is anticipated to govern the formation of exotic spin textures reported recently in cubic chiral magnets, like low-temperature tilted conical and skyrmion lattice (SkL) states and metastable SkLs with various lattice geometry. Motivated by these findings, we quantified the cubic anisotropy in a series of CoZnMn-type cubic chiral magnets. We found that the strength of anisotropy is highly enhanced towards low temperatures. Moreover, not only the magnitude but also the character of cubic anisotropy drastically varies upon changing the Co/Mn ratio. We correlate these changes with temperature- and composition-induced variations of the helical modulation vectors, deformations of skyrmions, structural rearrangements of the metastable SkLs and the large enhancement of Gilbert damping. Similar studies on magnetic anisotropy are required for the quantitative, unified description of the known stable and metastable modulated spin textures and for the systematic exploration of novel ones in this large class of skyrmion hosts.

MAGNETIZATION AND INHOMOGENEOUS MAGNETOELECTRIC EFFECT IN A NANO-SIZED TWO-LAYER FERROMAGNETIC FILM WITH A COMBINED UNIAXIAL AND CUBIC ANISOTROPY IN LAYERS

A numerical study of the magnetization reversal of a two-layer exchange-coupled ferromagnetic plate of finite dimensions, which has a combined uniaxial anisotropy (of the "easy axis" type for the upper layer and «easy plane» for the lower one) and cubic anisotropy with orientation [111]. It is shown that, in the presence of cubic anisotropy, the ground state of magnetization turns out to be uniform in the plane of the film. However, there is discontinuity at the interface between the film layers. This inhomogeneity can lead to the appearance of electric polarization due to the magnetoelectric effect. The electric polarization vector in this case lies in the plane of the film. Its modulus increases with increasing cubic anisotropy. In addition, with an increase in cubic anisotropy, a hysteresis of electrical polarization is observed.