Two-dimensional half-metals MSi2N4 (M = Al, Ga, In, Tl) with intrinsic p-type ferromagnetism and ultrawide bandgaps

Abstract

Intrinsic half-metallic nanomaterials with 100% spin polarization are highly demanded for next-generation spintronic devices. Here, by using first-principles calculations, we have designed a class of new two-dimensional (2D) p-type half-metals, MSi₂N₄ (M = Al, Ga, In and Tl), which show high mechanical, thermal and dynamic stabilities. MSi₂N₄ not only have ultrawide electronic bandgaps for spin-up channels in the range of 4.05 to 6.82 eV but also have large half-metallic gaps in the range of 0.75 to 1.47 eV, which are large enough to prevent the spin–flip transition. The calculated magnetic moment is 1 μ_B per cell, resulting from polarized N1-p_x/p_y orbitals. Moreover, MSi₂N₄ possess robust long-range ferromagnetic orderings with Curie temperatures in the range of 35–140 K, originating from the interplay of N1–M–N1 superexchange interactions. Furthermore, spin dependent electronic transport calculations reveal 100% spin polarization. Our results highlight new promising 2D ferromagnetic half-metals toward future spintronic applications.