We propose two-dimensional (2D) Ising-type ferromagnetic semiconductors ${\mathrm{TcSiTe}}_3, {\mathrm{TcGeSe}}_3$, and ${\mathrm{TcGeTe}}_3$ with high Curie temperatures around 200–500 K. Owing to large spin-orbit couplings, the large magnetocrystalline anisotropy energy (MAE), large anomalous Hall conductivity, and large magneto-optical Kerr effect were discovered in these intriguing 2D materials. By comparing all possible 2D $M{\text{GeTe}}_3$ materials ($M=3d,4d,5d$ transition metals), we found a large orbital moment around $0.5{\mu }_B$ per atom and a large MAE for ${\mathrm{TcGeTe}}_3$. The large orbital moments are revealed to be from the comparable crystal fields and electron correlations in these Tc-based 2D materials. The microscopic mechanism of the high Curie temperature is also addressed. Our findings reveal the unique magnetic behaviors of 2D Tc-based materials and present a family of 2D ferromagnetic semiconductors with large MAE and Kerr rotation angles that would have wide applications in designing spintronic devices.

• Received 29 August 2019

DOI:https://doi.org/10.1103/PhysRevResearch.2.013002

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Published by the American Physical Society