Designing half-metallic ferromagnetism by a new strategy: an example of superhalogen modified graphitic C3N4

Abstract

Designing half-metallic ferromagnetism at atomic scale is always one of the hottest topics for the scientific community due to its potential in spintronics applications. Although the band alignment strategy is broadly adopted in semiconductor-based research, it has not touched the field of low-dimensional spintronics. Here, taking graphitic C₃N₄ (g-C₃N₄) as an example, we show that perfect half-metallic ferromagnetism can be realized through a band alignment strategy. According to the alignment of the valence band maximum (VBM) and the conduction band minimum (CBM) of g-C₃N₄, and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of superhalogens, BF₄ is predicted to be a promising building unit which induces half-metallic ferromagnetism in the g-C₃N₄ sheet by forming hybrid structures. Verified by density functional simulations, we found that a net magnetic moment of 1 μ_B per BF₄ is induced in the g-C₃N₄ sheet. The magnetic moment distributes evenly on the double-coordinated nitrogen atoms with ferromagnetic coupling, and dynamics simulations confirmed that the structure of g-C₃N₄ is well protected. Thus, our study proposes a promising way to design half-metallic ferromagnetism at atomic scale, which will evoke further experimental interest.