Ferromagnetism and half-metallicity in two-dimensional $M\mathrm{O} (M=\mathrm{Ga},\mathrm{In})$ monolayers induced by hole doping

Identification of two-dimensional (2D) materials with magnetic properties has received strong research attention in the development of advanced spin-based devices. By means of first-principles calculations, we investigate the stability, electronic properties, and the hole-doping-induced magnetic properties of metal oxide ($M\mathrm{O}, M=\mathrm{Ga},\mathrm{In}$) monolayers. They are intrinsically nonmagnetic stable semiconductors, with high energetic, vibrational, and thermal stability. Hole doping can switch them from nonmagnetic to ferromagnetic and turn them into half-metals over a wide range of hole densities. Monte Carlo simulations predict that the highest Curie temperature of the GaO monolayer can reach ∼125 K. Our results indicate that monolayer $M\mathrm{O}$ could be eligible candidate materials for 2D spintronic devices.

Figure 1

(a) Top and sides views of a single-layer $M\mathrm{O}$ in the $H$ phase. The unit cell is highlighted by red dashed lines; (b),(c) phonon dispersion spectra of $H$-GaO and $H$-InO monolayers, respectively.

Figure 2

Orbital projected band structures and total density of states of (a) $H$-GaO and (b) $H$-InO monolayers.

Figure 3

Magnetic moment and spin-polarization energy as a function of hole doping density, and spin-polarized orbital projected density of states under different hole doping concentrations of (a) $H$-GaO and (b) $H$-InO monolayers.

Figure 4

Monte Carlo simulation of the normalized magnetization of $H-M\mathrm{O}$ monolayers as a function of temperature, for various hole doping densities, as indicated in the figure.