Quasiparticle band structures, spontaneous polarization, and spin-splitting in noncentrosymmetric few-layer and bulk γ-GeSe

Group-IV monochalcogenides have attracted much attention due to their potential of ferroelectric and multiferroic properties. Recently, centrosymmetric gamma-phase GeSe in a double-layer honeycomb lattice has been theoretically predicted, but the synthesized showed noncentrosymmetric atomic structure, leading possibility ferroelectricity spin-splitting. Here, we study quasiparticle band structures, spontaneous polarization, spin-splitting gamma-GeSe using density functional theory GW calculations. Our results show that few-layer bulk semiconducting structures with indirect gaps, which depend almost linearly on reciprocal number layers. Spontaneous polarization occurs small charge transfer between layers, increases compressive strain, switching can be achieved by an interlayer translation energy barrier. Spin-splitting is found more significant at highest valence than lowest conduction band. provide insights into fundamental electronic properties layered semiconductor applicable devices ferroelectric/nonferroelectric junctions.