Spin-fermion model for skyrmions in MnGe derived from strong correlations

摘要

MnGe has been reported as a candidate for a three-dimensional (3D) skyrmion crystal in comparison to the two-dimensional (2D) skyrmion observed in most other B20 compounds like MnSi. In addition, the small-sized skyrmions in MnGe are desired properties for information storage. By performing the density functional theory (DFT) calculations and model simulations based on the DFT-informed tight-binding Hamiltonian, we explore the nature of the 3D skyrmion in MnGe. By invoking the dual nature of d electrons on Mn atoms, we propose a strong-correlation-derived spin-fermion model with an antiferromagnetic coupling between the localized and itinerant moments. This model could explain the drastic difference in magnetic moments between MnGe and MnSi compounds. In addition, we find that the 3D or 2D nature of skyrmions is dependent on the coupling strength.