First-Principles Prediction of κ-Ga₂O₃:N Ferromagnetism

Dilute magnetic semiconductors (DMSs) have attracted widespread interest due to their potential applications in data storage and spintronics. However, there is no relevant report on the ferromagnetism of κ-Ga2O3, which is crucial for the spintronics research of the wide-gap semiconductor Ga2O3. In this report, the ferromagnetism of κ-Ga2O3 with N doping was investigated based on density functional theory. N as a deep acceptor exhibits low defect formation energy in κ-Ga2O3. The p–p state interaction between N and O atoms results in the ferromagnetic coupling, which is responsible for the transformation of κ-Ga2O3 from nonmagnetic to ferromagnetic. A single N atom with spin-polarized 2p states in the band gap generates a total magnetic moment of 1.0 μB. The N–N pair interaction length extends up to 4.6 Å. Interestingly, additional hole carriers can enhance the p–p ferromagnetic coupling, which shows a half-metallic ferromagnetic ground state. The stability of the magnetism at room temperature was confirmed via ab initio molecular dynamics simulations. The Curie temperature exceeds room temperature and rises with increasing hole carrier density. This study will provide an important foundation for the application of Ga2O3 in the spintronics field.