Half-metals and half-semiconductors in a transition metal doped SnSe2 monolayer: a first-principles study

Abstract

Recently, a new two-dimensional (2D) semiconductor SnSe₂ monolayer has been grown by molecular beam epitaxy, and weak ferromagnetic behavior above room temperature in Mn-doped SnSe₂ thin films was also observed experimentally. Here, using first-principles calculations, we investigate the structural, electronic, and magnetic properties of an SnSe₂ monolayer doped with transition metals V, Cr, Mn, Fe, Co, Ni and Cu. The calculated formation energies indicate that it is energetically favorable and relatively easy to incorporate these transition metals except for Cu into the SnSe₂ monolayer under Se-rich conditions. Doping induces considerable magnetic moments except for the Ni-doped system. Long-range ferromagnetic order is observed for V, Cr and Fe doping, and Mn doping has a short-range ferromagnetic order. Cu doping has an antiferromagnetic ground state. Within generalized gradient approximation, interestingly, both ferromagnetic V doping and metastable ferromagnetic Cu doping exhibit half-metallicity. Both Mn- and Fe-doped SnSe₂ monolayers are half-semiconductors. These properties are governed by the transition metal 3d orbital splitting under the crystal field and p–d hybridization. Within hybrid functional or spin–orbit coupling, the V-doped SnSe₂ monolayer becomes a half-semiconductor, and the Cu-doped SnSe₂ monolayer is still a half-metal. These studies indicate the promising spintronic applications for 2D semiconductor SnSe₂ doped by transition metals.