Giant proximity exchange and flat Chern band in 2D magnet-semiconductor heterostructures

TL;DR

This paper demonstrates significant proximity exchange effects and the emergence of flat Chern bands in 2D magnet-semiconductor heterostructures, opening pathways for spintronics and strongly correlated electronic states.

Contribution

First-principles calculations reveal large exchange splitting and flat Chern bands in vdW heterostructures, highlighting potential for novel quantum phenomena and device applications.

Findings

Proximity exchange splitting of 14 meV in MoS₂/CrBr₃ heterostructure

Discovery of flat Chern bands at specific magnetization values

Magnetic proximity induces anomalous Hall effect enabling detection of chiral spin textures

Abstract

Van der Waals (vdW) heterostructures formed by two-dimensional magnets and semiconductors have provided a fertile ground for fundamental science and for spintronics. We present first-principles calculations finding a proximity exchange splitting of 14 meV equivalent to an effective Zeeman field of 120 T in the vdW magnet-semiconductor heterostructure MoS$_2$/CrBr$_3$, leading to a 2D spin-polarized half-metal with carrier densities ranging up to $10^{13}$ cm$^{-2}$. We consequently explore the effect of large exchange coupling on the electronic bandstructure when the magnetic layer hosts chiral spin textures such as skyrmions. A flat Chern band is found at a "magic" value of magnetization $\overline{m} \sim 0.2$ for Schr\"odinger electrons, and it generally occurs for Dirac electrons. The magnetic proximity induced anomalous Hall effect enables transport-based detection of chiral spin textures, and flat Chern bands provides an avenue for engineering various strongly correlated states.