Electronic and magnetic properties of GeP monolayer modulated by Ge vacancies and doping with Mn and Fe transition metals.

In this work, Ge vacancies and doping with transition metals (Mn and Fe) are proposed to modulate the electronic and magnetic properties of GeP monolayers. A pristine GeP monolayer is a non-magnetic two-dimensional (2D) material, exhibiting indirect gap semiconductor behavior with an energy gap of 1.34(2.04) eV obtained from PBE(HSE06)-based calculations. Single Ge vacancy (Va) and pair Ge vacancies (pVa) magnetize the monolayer significantly with total magnetic moments of 2.00 and 2.02 , respectively. Herein, P atoms around the defect sites are the main contributors to the system magnetism. Similarly, the monolayer magnetization is induced by doping with Mn (Mn) and Fe (Fe) atoms. In these cases, total magnetic moments of 3.00 and 4.00 are obtained, respectively, and the system magnetism originates mainly from transition metal impurities. The calculated band structures assert the diluted magnetic semiconductor nature of Va and Fe systems, while pVa and Mn systems can be classified as 2D half-metallic materials. Further, the spin orientation in Mn- and Fe-doped GeP monolayers is studied. Results indicate the antiferromagnetic state in the case of doping with pair transition metal atoms. Regardless of the interatomic distance between dopant atoms, Mn-doped systems exhibit ferromagnetic half-metallicity, where the parallel spin orientation is energetically more favorable than the antiparallel configuration. In contrast, the antiparallel spin orientation is stable in Fe-doped systems, which show the antiferromagnetic semiconductor nature. Results presented herein may introduce new prospective 2D spintronic materials made from non-magnetic GeP monolayers.