title: Nature of the Insulating Ground State of the Two-Dimensional Sn Atom Lattice on SiC(0001).
abstract: Semiconductor surfaces with narrow surface bands provide unique playgrounds to search for Mott-insulating state. Recently, a combined experimental and theoretical study of the two-dimensional (2D) Sn atom lattice on a wide-gap SiC(0001) substrate proposed a Mott-type insulator driven by strong on-site Coulomb repulsion U within a single-band Hubbard model. However, our systematic density-functional theory (DFT) study with local, semilocal, and hybrid exchange-correlation functionals shows that the Sn dangling-bond state largely hybridizes with the substrate Si 3p and C 2p states to split into three surface bands due to the crystal field. Such a hybridization gives rise to the stabilization of the antiferromagnetic order via superexchange interactions. The band gap and the density of states predicted by the hybrid DFT calculation agree well with photoemission data. Our findings not only suggest that the Sn/SiC(0001) system can be represented as a Slater-type insulator driven by long-range magnetism, but also have an implication that taking into account long-range interactions beyond the on-site interaction would be of importance for properly describing the insulating nature of Sn/SiC(0001).
authors.affiliation: Department of Physics and Research Institute for National Sciences, Hanyang University, 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea.
authors.forename: Seho
authors.initials: S
authors.lastname: Yi
authors.affiliation: School of General Studies, Kangwon National University, 346 Jungang-ro, Samcheok-si, Kangwon-do, Korea.
authors.forename: Hunpyo
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Physics and Research Institute for National Sciences, Hanyang University, 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea.|Research Institute of Mechanical Technology, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Pusan 609-735, Korea.
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Department of Physics and Research Institute for National Sciences, Hanyang University, 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea.
authors.forename: Jun-Hyung
authors.initials: JH
authors.lastname: Cho