  The control of spin without magnetic field is one of challenges in developing
spintronic devices. In an attempt to solve this problem, we proposed a novel
hypothetic LaMn0.5Zn0.5AsO alloy from two experimentally synthesized rare earth
element transition metal arsenide oxides, i.e. LaMnAsO and LaZnAsO. On the
basis of the first-principles calculations with strong-correlated correction,
we found that the LaMn0.5Zn0.5AsO alloy is an antiferromagnetic semiconductor
at ground state, while bipolar magnetic semiconductor at ferromagnetic state.
Both electron and hole doping in the LaMn0.5Zn0.5AsO alloy induces the
transition from antiferromagnetic to ferromagnetic, as well as semiconductor to
half metal. In particular, the spin-polarization direction is switchable
depending on the doped carrier's type. As carrier doping can be realized easily
in experiment by applying a gate voltage, the LaMn0.5Zn0.5AsO alloy stands for
a promising spintronic material to generate and control the spin-polarized
carriers with electric field.
