Two-Dimensional Quaternary Transition Metal Sulfide CrMoA2S6 (A = C, Si, or Ge): A Bipolar Antiferromagnetic Semiconductor with a High Néel Temperature

Bipolar antiferromagnetic semiconductors (BAFSs) make up a class of spintronic materials, holding great promise for the manipulation of spin-polarized currents simply upon application of a voltage gate, but only a few two-dimensional (2D) BAFSs with a high Néel temperature (TN) have been reported. Here, we report a family of magnetic quaternary MM'A2S6 (M = V, Cr, Mn, or Fe; M' = Nb, Mo, Tc, or Ru; A = C, Si, Ge, or Sn) nanosheets by isovalent alloying layered transitional metal trisulfides (MAS3) based on first-principles calculations. Our results show that 2D CrMoA2S6 (A = C, Si, or Ge) nanosheets are BAFSs with band gaps ranging from 1.89 to 2.23 eV. Among them, 2D CrMoC2S6 has the highest TN of 556 K with robust magnetism against carrier doping and external in-plane strain due to a strong delocalization superexchange interaction between the Cr3+ and Mo3+ cations. This study establishes that CrMoC2S6 is an ideal prototype platform for realizing electric control of spin polarization in 2D materials.