Metallic charge density waves and surface Mott insulators for adlayer structures on semiconductors: extended Hubbard modeling

Abstract

Motivated by the recent experimental evidence of commensurate surface CDW in Pb/Ge(111) and Sn/Ge(111) $\sqrt{3}$-adlayer structures, as well as by the insulating states found on K/Si(111):B and SiC(0001), we have investigated the role of electron-electron interactions, and also of electron-phonon coupling, on the narrow surface state band originating from the dangling bond orbitals of the adsorbate. We model the problem by an extended two-dimensional Hubbard model at half-filling on a triangular lattice. We include an on-site Hubbard repulsion U and a nearest-neighbor V, plus a long-ranged Coulomb tail. The electron-phonon interaction is treated in the deformation potential approximation. We have explored the phase diagram of the model including the possibility of commensurate 3x3 phases, using mainly the Hartree-Fock approximation. For U larger than the bandwidth we find magnetic insulators, possibly corresponding to the situation in SiC and in K/Si. For smaller U, the inter-site repulsion V can stabilize metallic CDW phases, reminiscent of the 3x3 structures of Sn/Ge, and possibly of Pb/Ge.

10 pages, 3 figures, presented at ECOSS-17 sept 1997

References in corpus (1)

• First Principles Calculations of Charge and Spin Density Waves of sqr3-Adsorbates on Semiconductors

Cited by in corpus (10)

• Charge density waves and surface Mott insulators for adlayer structures on semiconductors: extended Hubbard modeling
• The Mott Metal-Insulator transition in the half-filled Hubbard model on the Triangular Lattice
• SiC(0001): a surface Mott-Hubbard insulator
• The order-disorder character of the (3x3) to (sqrt3 x sqrt3)R30° phase transition of Sn on Ge(111)
• First Principles Calculations of Charge and Spin Density Waves of sqr3-Adsorbates on Semiconductors
• Uncertainty principle for experimental measurements: Fast versus slow probes
• Charge density wave in single-layer Pb/Ge(111) driven by Pb-substrate exchange interaction
• Charge-density-wave formation by Van Hove nesting in the α-phase of Sn/Ge(111)
• Metallic Surface Reconstruction Driven by Frustrated Antiferromagnetism
• Spectroscopic fingerprints of a surface Mott-Hubbard insulator: the case of SiC(0001)