Tunable Magnetism and Half-Metallicity in Hole-doped Monolayer GaSe

TL;DR

This study uses first-principles calculations to show that hole doping in monolayer GaSe induces tunable ferromagnetism and half-metallicity, driven by exchange splitting at a van Hove singularity in the valence band.

Contribution

It reveals a novel way to induce and control magnetism and half-metallicity in monolayer GaSe through hole doping, with detailed electronic structure analysis.

Findings

Hole doping induces ferromagnetism in monolayer GaSe.

Magnetic moment reaches ~1 μB per carrier at specific doping levels.

System exhibits half-metallicity before magnetic moment declines.

Abstract

We find, through first-principles calculations, that hole doping induces a ferromagnetic phase transition in monolayer GaSe. Upon increasing hole density, the average spin magnetic moment per carrier increases and reaches a plateau near 1.0 $\mu_{\rm{B}}$/carrier in a range of $3\times 10^{13}$/cm$^{2}$-$1\times 10^{14}$/cm$^{2}$ with the system in a half-metal state before the moment starts to descend abruptly. The predicted magnetism originates from an exchange splitting of electronic states at the top of the valence band where the density of states exhibits a sharp van Hove singularity in this quasi-two-dimensional system.