Magnetic-Order Induced Spectral-Weight Redistribution in a Triangular Surface System

Abstract

The Sn-induced √ 3 × √ 3 surface reconstruction on Si(111) has been investigated by materialspecific many-body calculations and by angle-resolved photoelectron spectroscopy (ARPES). This triangular surface system in the low adatom coverage regime is governed by rather localized dangling bond orbitals with enhanced electronic correlations and it is prone to exhibit magnetic frustration. We find a rather good overall agreement of the spectral function and its temperature-dependence between theory and experiment. Changes in the ARPES band topology in comparison to the density functional calculations can be explained as a spectral weight redistribution with respect to an additional symmetry which is not due to any geometrical change. This new symmetry corresponds to a magnetic order, which is found to be more complex than the canonical 120 • anti-ferromagnetic order on a triangular lattice with nearest-neighbor coupling only.

Long-Range Coulomb Interactions in Surface Systems: A First-Principles Description within Self-Consistently CombinedGWand Dynamical Mean-Field Theory

“…Systems of adatoms on semiconducting surfaces, such as Si(111):X with X=Sn, C, Si, Pb, have been suggested [1] to be good candidates for observing low-dimensional correlated physics. Commonly considered to be realizations of the one-band Hubbard model and toy systems for investigating many-body physics on the triangular lattice, such surfaces have been explored experimentally [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and theoretically [19][20][21][22][23][24][25][26][27][28][29][30][31].These so-called α-phases show a remarkable variety of interesting physics including commensurate charge density wave (CDW) states [5,6,9] and isostructural metal to insulator transitions (MIT) [14]. However, while specific systems and/or phenomena have been investigated also theoretically, a comprehensive understanding including materials trends is still lacking.…”