Mott Insulating Ground State on a Triangular Surface Lattice

Abstract
Momentum-resolved direct and inverse photoemission spectra of the K/Si111(3×3)R30°B interface reveals the presence of strongly localized surface states. The K overlayer remains nonmetallic up to the saturation coverage. This system most likely presents the first experimental realization of a frustrated spin 1/2 Heisenberg antiferromagnet on a two-dimensional triangular lattice.