Tunable electronic structure and magnetic anisotropy in bilayer ferromagnetic semiconductor Cr2Ge2Te6

TL;DR

This study uses first-principles calculations to explore how strain and doping can tune the magnetic properties and electronic structure of bilayer Cr2Ge2Te6, a 2D ferromagnetic semiconductor, revealing pathways to enhance ferromagnetism and induce half-metallicity.

Contribution

It identifies critical strain and doping conditions to stabilize ferromagnetism and control magnetic anisotropy in bilayer Cr2Ge2Te6, providing new insights for 2D magnetic material engineering.

Findings

Strain and doping can enhance ferromagnetic stability.

Tensile strain induces phase transition to antiferromagnetism.

Compressive strain and doping can reverse spin polarization.

Abstract

The emergence of ferromagnetism in two-dimensional van der Waals materials has aroused broad interest. However, the ferromagnetic instability has been a problem remained. In this work, by using the first-principles calculations, we identified the critical ranges of strain and doping for the bilayer Cr2Ge2Te6 within which the ferromagnetic stability can be enhanced. Beyond the critical range, the tensile strain can induce the phase transition from the ferromagnetic to the antiferromagnetic, and the direction of magnetic easy axis can be converted from out-of-plane to in-plane due to the increase of compressive strain, or electrostatic doping. We also predicted an electron doping range, within which the ferromagnetism can be enhanced, while the ferromagnetic stability was maintained. Moreover, we found that the compressive strain can reverse the spin polarization of electrons at the conduction band minimum, so that two categories of half-metal can be induced by controlling electrostatic doping in the bilayer Cr2Ge2Te6. These results should shed a light on achieving ferromagnetic stability for low-dimensional materials.