Nanometric skyrmion lattice from anisotropic exchange interactions in a centrosymmetric host
Max Hirschberger, Satoru Hayami, Yoshinori Tokura
Abstract
Abstract Skyrmion formation in centrosymmetric magnets without Dzyaloshinskii–Moriya interactions was originally predicted from unbiased numerical techniques. However, no attempt has yet been made, by comparison to a real material, to determine the salient interaction terms and model parameters driving spin-vortex formation. We identify a Hamiltonian with anisotropic exchange couplings, local ion anisotropy, and four-spin interactions, which is generally applicable to this class of compounds. In the representative system Gd 3 Ru 4 Al 12 , anisotropic exchange drives a fragile balance between helical, skyrmion lattice (SkL), and transverse conical (cycloidal) orders. The model is severely constrained by the experimentally observed collapse of the SkL with a small in-plane magnetic field. For the zero-field helical state, we further anticipate that spins can be easily rotated out of the spiral plane by a tilted magnetic field or applied current.