First-Principles Calculations of Room-Temperature Antiferromagnetism in Crystalline Transition-Metal Borate Nanosheets: Implications for Spintronics Applications

Two-dimensional (2D) antiferromagnetic materials with room-temperature magnetism and ambient stability are highly desirable for practical applications of antiferromagnetic spintronic nanodevices; however, they have been rarely explored. Here, a new family of antiferromagnetic transition-metal borate TMBO3 (TM = V, Cr, Mn, Fe) nanosheets, 2D counterparts of calcite-type TMBO3 materials, are reported based on first-principles calculations. 2D TMBO3 crystals are antiferromagnetic semiconductors with band gaps ranging from 2.92 to 5.09 eV and high lattice thermodynamic stability up to 1500 K. Particularly, the estimated Néel temperature (TN) of a 2D CrBO3 crystal is 397 K, which can be further enhanced to 672 K by applying a biaxial strain. Strong chemical bonding between transition-metal cations and [BO3]3– anions endows 2D TMBO3 crystals with ambient stability against oxidative degradation and molecular adsorption on the surface. This study provides a promising prototype of antiferromagnetic TMBO3 nanosheets for practical applications of antiferromagnetic spintronic nanodevices, such as read-head devices and magnonic transport-based devices.