Title: Chiral Quantum well Rashba splitting in Sb monolayer on Au(111)

Abstract: We present atomic and electronic structure investigations of Single-layer Sb(110) rhombohedral crystal formed on Au(111) substrate. Low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) reveal a pure 2D Sb stripe structure, composed by a pair of Sb(110) unit cell located in a chiral configuration with mirror symmetry broken along the x axis direction. Based on angle-resolved photoemission spectroscopy (ARPES) measurement and Sb-weighted band structure from density functional theory calculations, we report the unambiguous determination of one pair of Rashba-type splitting band from the 2D Sb film, exhibiting a chiral symmetry in the electronic structure with the crossing point located at point and point, respectively. Moreover, From dI/dV spectra and calculated density of states(DOS), the quantum well(QW) Rashba-type states at different energy induced by the in-plane mirror symmetry broken in Sb stripe structure have been identified, and the orbital decomposition of projected band structure indicates hybridization between Sb py state and Au state can modify the spin splitting of QW states due to the intrinsic large SOC of Au state introduced into the QW states.