Magnetic anisotropic effects and electronic correlations in MnBi ferromagnet

TL;DR

This study uses advanced computational methods to analyze MnBi's electronic structure and magnetic properties, revealing the importance of Coulomb correlations, spin-orbit coupling, and hybridization in understanding its magnetic behavior and anisotropy.

Contribution

The paper introduces a comprehensive LSDA+$U$ approach to accurately describe MnBi's magnetic moments, anisotropy, and spin reorientation, highlighting the role of Coulomb correlations and spin-orbit effects.

Findings

Coulomb correlations improve magnetic moment and anisotropy energy predictions.

Inversion of Bi-Bi exchange interaction causes spin reorientation at 90 K.

Strong spin-orbit coupling and hybridization influence magnetic properties.

Abstract

The electronic structure and numerous magnetic properties of MnBi magnetic systems are investigated using local spin density approximation (LSDA) with on-cite Coulomb correlations (LSDA+$U$) included. We show that the inclusion of Coulomb correlations provides a much better description of equilibrium magnetic moments on Mn atom as well as the magnetic anisotropy energy (MAE) behavior with temperature and magneto-optical effects. We found that the inversion of the anisotropic pairwise exchange interaction between Bi atoms is responsible for the observed spin reorientation transition at 90 K. This interaction appears as a result of strong spin orbit coupling on Bi atoms, large magnetic moments on Mn atoms, significant $p-d$ hybridization between Mn and Bi atoms, and it depends strongly on lattice constants. A better agreement with the magneto-optical Kerr measurements at higher energies is obtained. We also present the detailed investigation of the Fermi surface, the de Haas-van Alphen (dHvA) effect and the X-ray magnetic circular dichroism in MnBi.