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

The alpha-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 root 3 x root 3) domains, while the Sn reconstruction reveals a (root 3 x root 3) symmetry. The Rashba splitting of the highest occupied Mott state was found to be Delta k = 0.05 angstrom(-1), i.e., the alpha-Sn phase should be termed a weakly spin-orbit coupled Mott system.