Regulating the electronic properties of the WGe2N4 monolayer by adsorption of 4d transition metal atoms towards spintronic devices

Abstract

We study the regulation of the electronic and spin transport properties of the WGe₂N₄ monolayer by adsorbing 4d transition metal atoms (Y–Cd) using density functional theory combined with non-equilibrium Green's function. It is found that the adsorption of transition metal atoms (except Pd, Ag and Cd atoms) can introduce a magnetic moment into the WGe₂N₄ monolayer. Among the transition metal atoms, the adsorption of Nb and Rh atoms transforms WGe₂N₄ from a semiconductor to a half-metal and a highly spin-polarized semiconductor, respectively. The half-metallic Nb-adsorbed WGe₂N₄ system is selected to investigate the spin transport properties, and a high magnetoresistance ratio of 10⁷% is achieved. In both parallel and antiparallel magnetization configurations, the spin filtering efficiency reaches close to 100% in the whole bias range, and the antiparallel magnetization configuration exhibits a dual spin filtering effect with a rectification ratio of up to 10⁴. Our study predicts that the adsorption of 4d transition metal heteroatoms is an effective method to regulate the electronic and magnetic properties of WGe₂N₄ towards high-performance spintronic devices.