Recent studies have demonstrated that two-dimensional intrinsic magnetic materials with high Curie temperature $\left(T_{\text{c}}\right)$ and large magnetic anisotropy energy (MAE) are highly desirable for future spintronics. After careful investigations through density functional theory, bipolar ${\mathrm{VSi}}_2{\mathrm{As}}_4$ and ${\mathrm{VGe}}_2{\mathrm{As}}_4$ monolayers, with semiconductor valence and conduction band edges fully spin polarized in different spin directions, are demonstrated to be highly stable and have in-plane ferromagnetism (FM) with large MAE of $\sim 5.5$ meV. The FM interaction is found to be dominated by the superexchange between d orbitals of V atoms through p orbitals of anions. More interestingly, $T_{\text{c}}$ is estimated to be $\sim 900$ K through Monte Carlo simulation, which is significantly higher than room temperature. In addition, both MAE and $T_{\text{c}}$ can be substantially regulated and increased under biaxial strain and the transition from FM semiconductors to metals will occur. Our calculations and analyses indicate that ${\mathrm{VSi}}_2{\mathrm{As}}_4$ and ${\mathrm{VGe}}_2{\mathrm{As}}_4$ monolayers are ideal systems for the fundamental understanding of magnetic physics as well as building blocks for magnetoelastic applications, high-temperature, or/and gate-tunable spintronic nanodevices.

• Received 2 September 2022
• Accepted 21 November 2022

DOI:https://doi.org/10.1103/PhysRevB.106.235401