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.