α -Sn phase on Si(111): Spin texture of a two-dimensional Mott state

The α-Sn reconstruction on Si(111) is a prototype system for a two-dimensional Mott phase. In this study we performed spin-resolved photoemission experiments and analyzed in detail the spin structure of this electronically correlated surface state. The analysis of the spin-integrated bands as well as the spin texture of the surface states along different crystallographic directions provide clear evidence for the formation of collinear antiferromagnetic (2√3×√3) domains, while the Sn reconstruction reveals a (√3×√3) symmetry. The Rashba splitting of the highest occupied Mott state was found to be Δk=0.05Å−1, i.e., the α-Sn phase should be termed a weakly spin-orbit coupled Mott system.