Tunable electronic structures and half-metallicity in two-dimensional InSe functionalized with magnetic superatom

Based on first-principles calculations, we investigate the geometric, energetic and electronic properties of two-dimensional (2D) InSe functionalized with magnetic superatoms (MnCl3). As a nonmagnetic semiconductor, 2D InSe exhibits non-covalent interaction with MnCl3 and provides an ideal substrate for the assembly of magnetic superatoms. We show that with a low coverage of MnCl3, the functionalized system behaves as a magnetic semiconductor with spin-polarized superatomic states residing inside the energy gap of InSe. When the coverage becomes higher, the system has one spin channel crossing Fermi level while the other remains insulating, thus being half-metallic. We further demonstrate electric field effects on the functionalized system, and reveal that half metal with 100% spin polarization can be achieved at a lower coverage due to the field induced charge transfer, which downshifts the unoccupied bands of one spin component so that they become partially filled. These findings are generally applicable, demonstrating the great promise of combining superatom assembly with electric gating for controllable and versatile 2D spintronics.