Semiconducting Cr2BN monolayer with antiferromagnetic order

The key to the next-generation spintronic devices is to design above-room-temperature two-dimensional antiferromagnets with large magnetic moments and anisotropy energies. We propose a design strategy to maximize the utilization of d electrons and the strong coupling of transition-metal atoms. The designed semiconducting Cr2BN monolayer consists of hexagonal Cr6BN tiles centered by BN dimers. Compared to isolated B or N atoms, the BN dimer in Cr2BN can reduce the charges donated by Cr atoms, whereas the short Cr-Cr distance favors strong direct-exchange coupling interaction. These features make the Cr2BN monolayer checkerboard antiferromagnetic with a high Neel temperature of 874 K, a large magnetic anisotropy energy of 103 mu eV/Cr, and a large magnetic moment of 3.79 mu B. High structural stability, originating from the covalent BN dimer and Cr-B/N ionic bond, renders Cr2BN a good candidate for experimental synthesis.