Spin Transport and Spin Thermoelectric Transport in 2D Mn-Doped Blue Phosphorene with High Curie Temperature and Half-Metallicity

Although 2D phosphorene has exhibited promising applications in electronic and optoelectronic devices with high carrier mobility and high on/off ratio, the nonmagnetism in pristine phosphorene hinders its potential applications in spintronic devices. In this work, using first-principles, Monte Carlo simulations, and the nonequilibrium Green’s function method, we investigate the structural, magnetic, and electronic properties as well as the spin transport and spin thermoelectric transport properties for Mn-doped monolayer blue phosphoren (Blue-P). We find that Mn-doped Blue-P is structurally stable and thermally stable, and it exhibits ferromagnetism above room temperature. Interestingly, the doped system is a half-metal with complete spin polarization of electrons around the Fermi level, which is robust with respect to the doping concentration. The spin transport properties indicate an excellent spin-filtering effect and a high magnetoresistance ratio (up to 10⁵%), which are explained from the calculated bias-voltage- and spin-dependent band structures and the spin-dependent transmission eigenstates and pathways. In addition, the spin thermoelectric transport properties show a thermal spin filtering effect, a large spin Seebeck coefficient, and a low thermal conductivity. A high spin thermoelectric figure of merit accompanied by a small charge thermoelectric figure of merit can be obtained by adjusting the chemical potential and the temperature. These results suggest that 2D Mn-doped Blue-P is a promising candidate for versatile spintronic and spin caloritronic applications.