Strong-Correlation Derived Spin-Fermion Model for Skyrmions in MnGe

TL;DR

This paper develops a new spin-fermion model based on strong electron correlations to explain the 3D skyrmions in MnGe, highlighting the role of coupling strength in skyrmion dimensionality and magnetic properties.

Contribution

It introduces a strong-correlation derived spin-fermion model informed by DFT calculations, explaining skyrmion nature and magnetic differences in MnGe.

Findings

The model explains the magnetic moment differences between MnGe and MnSi.

Skyrmion dimensionality depends on coupling strength.

The dual nature of d-electrons is key to understanding skyrmion properties.

Abstract

MnGe has been reported as a candidate of 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 a 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 of magnetic moments between MnGe and MnSi compounds. In addition, we find that the 3D or 2D nature of skyrmions are dependent on the coupling strength.