Huge perpendicular magnetic anisotropy in a 12-fold planar hypercoordinate W@B12(NCCN)3 monolayer

Two-dimensional (2D) materials with planar hypercoordinate motifs are attractive in terms of both fundamental science and technological applications. Herein, we construct a stable hexagonal 2D W@B12(NCCN)3 monolayer using W@B12 cluster as a building block and –NCCN– as a bridge linker. Multi-center bonding analysis reveals that the abundant 3c–1e B–W–Β σ bonds are responsible for the stability of a 12-fold coordinated W@B12 wheel, which has the highest coordination number reported for a planar system. Moreover, 3c–1e Β−Ν−Β, 4c − 1e N–C–C–N, and 13c − 1e W–B12 π bonds together form big delocalized π bonds, endowing 2D W@B12(NCCN)3 with unusual stability. Remarkably, 2D W@B12(NCCN)3 is a robust ferromagnetic half-metal with a large orbital moment anisotropy of 1.3 μB, a high out-of-plane magnetic anisotropy energy of 199 meV/atom, and a high Curie temperature of 150 K, which provides a potential candidate for high-density memory devices. These findings provide vital guidance for the design of 2D magnets with planar hypercoordination and unusual functionality.