Electronic structure of two-dimensional boron sheets

Boron is the fifth element in the periodic table and hosts rich physical and chemical properties. Inspired by the fruitful results of graphene, the possibility for the existence of two-dimensional boron sheets have been extensively explored in the recent years. Here, we synthesized two types of monolayer boron sheets on Ag(111) substrate. Angle-resolved photoemission spectroscopy measurements reveal the existence of metallic bands from these boron sheets, distinct from the semiconducting behavior of other boron allotropes. Combined with first-principles calculations, we demonstrate that the interaction between the boron layer and the substrate is relatively weak and the band structure of free-standing boron sheets remain largely intact after being adsorbed on Ag(111). References: 1. B. Feng, \quad et al., Experimental realization of two-dimensional boron sheets. Nat. Chem. 8, 563(2016). 2. B. Feng, et al., Direct evidence of metallic bands in a monolayer boron sheet. Phys. Rev. B 94, 041408(R)(2016).