Surface decoration of phosphorene nanoribbons with 4d transition metal atoms for spintronics

The recent production of phosphorene nanoribbons provides a platform for designing phosphorene-based high-speed electronic devices. Introducing a magnetic moment to phosphorene nanoribbons for spintronics application is attractive. Based on density functional theory combined with the non-equilibrium Green's function method, the electronic, magnetic and spin-polarized transport properties of phosphorene nanoribbons modified by adsorption and substitutional doping of 4d transition metal atoms (Y, Zr, Nb and Mo) are investigated systematically. The results show that both the adsorption and the doping of 4d transition metal atoms can introduce a magnetic moment into phosphorene nanoribbons, except the Y- and Nb-doping cases. The adsorption shows superior performance in terms of modulating the electronic and magnetic properties of phosphorene nanoribbons compared to substitutional doping, exhibiting higher spin polarization near the Fermi level with a narrower band gap. This discrepancy originates from the different electronic redistribution in the adsorption and doping situations. Furthermore, the nanoribbons with adsorbed 4d transition metal atoms exhibit excellent spin-polarized transport properties: a giant magnetoresistance ratio of the Mo-adsorbed nanoribbon reaches over 108 under low bias; the Y-Mo-adsorbed nanoribbons with parallel spin configurations show a spin filtering effect of about 100% with the bias larger than 0.1 V, and those with antiparallel spin configurations exhibit a dual spin filtering effect in an applied bias range of (-0.2 V, 0.2 V). Our results demonstrate that 4d-transition-metal-atom adsorption is a favourable approach to modify the electronic, magnetic and transport properties of phosphorene nanoribbons, thus providing a reference for the rational design of spintronic devices based on phosphorene nanoribbons.