Engineering the half-metallic and magnetic semiconductor natures in gallium phosphide monolayer towards spintronic applications

In this work, magnetism engineering in the Gallium phosphide (GaP) monolayer is explored in order to create new two-dimensional (2D) spintronic materials. Pristine monolayer is a non-magnetic indirect gap semiconductor with band gap of 1.61(2.49) eV obtained from the PBE(HSE06)-based calculations. Both ionic and covalent characters form the Ga-P chemical bond, which are generated by the charge transfer and electronic hybridization, respectively. It is found that creating a single Ga vacancy magnetizes significantly GaP monolayer (VGa), where a large total magnetic moment of 2.88 μB is obtained and magnetic properties are produced mainly by P atoms around the defect site. Meanwhile, GaP monolayer is metallized under effects of single P vacancy, where the non-magnetic nature is preserved. Significant magnetization is also achieved by doping with alkali (Li and Na - LiGa and NaGa) and alkaline earth (Be and Mg - BeGa and MgGa) metals. In these cases, total magnetic moments of 2.00 and 1.00 μB are obtained, respectively. Besides, doping with S (SP) and Se (SeP) atoms induces weaker magnetization, which is reflected in smaller total magnetic moments of 0.60 and 0.96 μB, respectively. Interestingly, the half-metallicity is observed in VGa, BeGa, and MgGa systems; while LiGa, NaGa, and SeP systems exhibit the diluted magnetic semiconductor behavior. In contrast, Cl (ClP) and Br (BrP) impurities induces no magnetism in GaP monolayer. However both ClP and BrP systems have energy gap of 0.76 eV, which corresponds to a reduction of the order of 52.80% from that of pristine monolayer. Results presented herein may introduce efficient methods to modify the GaP monolayer electronic and magnetic properties, such that new multifunctional 2D materials can be created for spintronic and optoelectronic applications.