Interlayer coupling rotatable magnetic easy-axis in MnSe2 mono- and bi-layers

TL;DR

This paper reveals how interlayer coupling in MnSe2 monolayers and bilayers can significantly change the magnetic easy-axis orientation, influenced by orbital occupations, with implications for spintronics.

Contribution

It demonstrates that interlayer coupling affects magnetic easy-axis orientation through orbital occupation changes, especially involving Se atoms, which was previously underexplored.

Findings

Monolayer MnSe2 easy-axis tilts 67° from z-axis.

Bilayer MnSe2 easy-axis aligns with z-axis.

Orbital occupations near Fermi level influence easy-axis orientation.

Abstract

Interlayer coupling plays a critical role in tuning the electronic structures and magnetic ground states of two-dimensional materials, influenced by the number of layers, interlayer distances, and stacking order. However, its effect on the orientation of the magnetic easy axis remains underexplored. In this study, we demonstrate that interlayer coupling can significantly alter the magnetic easy-axis orientation, as shown by the magnetic easy-axis of monolayer 1T-MnSe2 tilting 67{\deg} from the z-axis, while aligning with the z-axis in the bilayer. This change results from variations in orbital occupations near the Fermi level, particularly involving nonmetallic Se atoms. Contrary to the traditional focus on magnetic metal atoms, our findings reveal that Se orbitals play a key role in influencing the easy-axis orientation and topological Chern numbers. Furthermore, we validated our conclusions by changing stacking orders, introducing charge doping, applying in-plane biaxial strains, and substituting non-metallic atoms. Our results highlight the pivotal role of interlayer coupling in tuning the magnetic properties of layered materials, with important implications for spintronic applications.