High Curie temperature and perfect spin filtering effect in a single layer Ga₂O₃ magnetic tunnel junction

The electronic structure and magnetic properties of single layer Ga₂O₃ in the presence of Ga and O vacancies are studied by first principles method based on density functional theory. The results show that the introduction of Ga vacancy (V_Ga) leads to a non-zero magnetic moment in single-layer two-dimensional (2D) Ga₂O₃ while V_O does not. We find that Ga vacancies in two different symmetric positions can lead to spin polarized ground states. Notably, when the V_Ga ratio is greater than 1/16 (indicating one Ga vacancy per 16 Ga atoms), single-layer 2D Ga₂O₃ exhibits semi-metallic properties and its spin polarization reaches 100% at the Fermi level. Calculations of these two Ga vacancy systems also indicate a potential long-range ferromagnetic order at a high Curie temperature (355.8 K). Finally, a single layer 2D Ga₂O₃ with high GaI vacancy (V_GaI) ratio can be used as the ferromagnetic layer to obtain the magnetic tunnel junction (MTJ) with high spin filtering effect at the Fermi level. Ga vacant Ga₂O₃/MgO/Ga vacant Ga₂O₃ MTJ exhibits excellent spin-filtering effect (with 100% spin polarization) and a giant tunneling magneto resistance (TMR) ratio (up to 1.12 × 10³%). The results of this paper show that the MTJ based on two-dimensional Ga₂O₃ with room temperature ferromagnetism exhibits reliable performance, showing the possibility of potential applications in spintronics.