Electronic properties and quasi-particle model of monolayer MoSi${}_2$N${}_4$

Abstract

By a combined study with first-principles calculations and symmetry analysis, we theoretically investigate the electronic properties of monolayer MoSi${}_2$N${}_4$. While the spin-orbital coupling results in bands splitting, the horizontal mirror symmetry locks the spin polarization along z-direction. In addition, a three-band tight-binding model is constructed to describe the low-energy quasi-particle states of monolayer MoSi${}_2$N${}_4$, which can be generalized to strained MoSi${}_2$N${}_4$ and its derivatives. The calculations using the tight-binding model show an undamped $\sqrt{q}$-dependent plasmon mode that agrees well with the results of first-principles calculations. Our model can be extended to be suitable for future theoretical and numerical studies of low-energy properties in MoSi${}_2$N${}_4$ family materials. Furthermore, the study of electronic properties of monolayer MoSi${}_2$N${}_4$ paves a way for its applications in spintronics and plasmonics.

8 pages, 8 figures