Ferromagnetism with above-room-temperature Curie temperature in Fe-doped β-Ga2O3 studied by first-principles calculations

Induced by the spin-polarized double-exchange interaction between the 3d orbitals of Fe atoms and O-2p orbitals near the O/Ga vacancy complexes, the origin of magnetism in β-Ga2O3 is investigated by using geometry optimization and energy calculation based on the first-principles generalized gradient approximation Hubbard + U method of density-functional theory. The results show that the formation energy of Fe2+ in the β-Ga2O3 matrix is lower than that of Fe3+, and the system is more stable when the Ga or O vacancies (VGa or VO) are adjacent to the Fe lattice position. It is found that the β-Ga31Fe2+/3+O47 and β-Ga30Fe2+/3+O48 systems all exhibit ferromagnetism with above-room-temperature Curie temperature. β-Ga30Fe2+/3+O48 (i.e., with Fe2+/3+ and VGa) has more spin-polarized O atoms in the same direction. The magnetism originates from the double-exchange interaction of the coupling and hybridization of the Fe-3d state of Fe3+ and the O-2p state, which increases the magnetic moment of the β-Ga30Fe3+O48 system. This study provides a theoretical reference for designing and preparing new β-Ga2O3-based dilute magnetic semiconductors and related spintronic and optoelectronic devices.