Regulating the electronic properties of the WGe 2 N 4 monolayer by adsorption of 4d transition metal atoms towards spintronic devices.

We study the regulation of the electronic and spin transport properties of the WGe 2 N 4 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 WGe 2 N 4 monolayer. Among the transition metal atoms, the adsorption of Nb and Rh atoms transforms WGe 2 N 4 from a semiconductor to a half-metal and a highly spin-polarized semiconductor, respectively. The half-metallic Nb-adsorbed WGe 2 N 4 system is selected to investigate the spin transport properties, and a high magnetoresistance ratio of 10 7 % 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 10 4 . Our study predicts that the adsorption of 4d transition metal heteroatoms is an effective method to regulate the electronic and magnetic properties of WGe 2 N 4 towards high-performance spintronic devices.