Adsorption-enhanced spin-orbit coupling of buckled honeycomb silicon

We have studied the electronic structures of quasi-two-dimensional buckled honeycomb silicon (BHS) saturated by atomic hydrogen and fluorine by means of first-principles calculations. The graphene-like hexagonal silicon with chair configurations can be stabilized by atomic hydrogen and fluorine adsorption. Together with a magnetic ground state, large spin orbit coupling (SOC) of BHS saturated by hydrogen on either side (Semi-H-BHS) indicated by the band splitting of sigma bond at Gamma point in the Brillouin zone is attributed to the intermixing between the density of states of hydrogen atoms and pi bonds of unpassivated Si-2 around the Fermi level. The Zeeman spin splitting is most likely caused by the internal electric field induced by asymmetric charge transfer. (C) 2016 Elsevier B.V. All rights reserved.