Electronic structures calculation of Si1−xSnx compound alloy using interacting quasi-band model

AbstractThe crystal structures of a new family of superconductors containing a Bi square net and their electronic structures around the Fermi level have been reviewed. The structures of these compounds can be viewed as stacked layers denoted by [Bi][(RE)(M2Bi2)(RE)] RE = rare earth or alkaline earth metal, M = transition metal. Flat/steep band features are shown to exist in all these new superconductors, though the pairing mechanisms may be very different. The Dirac Fermion behavior is reviewed and its implications are discussed.

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A "FLAT/STEEP BAND" MODEL FOR SUPERCONDUCTIVITY

International Journal of Modern Physics B ◽

10.1142/s0217979205027895 ◽

2005 ◽

Vol 19 (01n03) ◽

pp. 29-36 ◽

Cited By ~ 13

Author(s):

S. DENG ◽

A. SIMON ◽

J. KÖHLER

Keyword(s):

First Principles ◽

Electronic Structures ◽

Electronic States ◽

Low Energy ◽

Coupling Constants ◽

Flat Band ◽

Band Model ◽

Phonon Coupling ◽

Pairwise Interactions ◽

Electron Phonon Coupling

Based on a viewpoint of chemical pairwise interactions between electrons, a Hamiltonian was proposed for the "flat/steep band" scenario. This model has been studied analytically, and numerically with the first-principles method. With Hg and MgB 2 as examples, we have explained the characteristics of this model and observed peak-like structures of the electron-phonon coupling constants λ(q) in q space. The strong coupling of the "flat band" electrons with phonons has been corroborated by developing a new functional Psib(Φ), through which we can quantitatively compare different electronic states in coupling to a specific phonon. The relevance of our model to an electronic inhomogeneity is also discussed. Investigations on experimental and theoretical low-energy electronic structures of superconductors support our flat/steep scenario.

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The Nature of Oxide Surfaces: Topographic and Electronic Structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150666 ◽

1993 ◽

Vol 51 ◽

pp. 966-967

Author(s):

Dawn A. Bonnell ◽

Yong Liang

Keyword(s):

Transition Metal Oxides ◽

Electronic Structures ◽

Recent Progress ◽

Spatial Localization ◽

Level Of Detail ◽

Scanning Tunneling ◽

Oxide Surfaces ◽

Tunneling Microscopy ◽

Considerable Effort ◽

Complete Understanding

Recent progress in the application of scanning tunneling microscopy (STM) and tunneling spectroscopy (STS) to oxide surfaces has allowed issues of image formation mechanism and spatial resolution limitations to be addressed. As the STM analyses of oxide surfaces continues, it is becoming clear that the geometric and electronic structures of these surfaces are intrinsically complex. Since STM requires conductivity, the oxides in question are transition metal oxides that accommodate aliovalent dopants or nonstoichiometry to produce mobile carriers. To date, considerable effort has been directed toward probing the structures and reactivities of ZnO polar and nonpolar surfaces, TiO2 (110) and (001) surfaces and the SrTiO3 (001) surface, with a view towards integrating these results with the vast amount of previous surface analysis (LEED and photoemission) to build a more complete understanding of these surfaces. However, the spatial localization of the STM/STS provides a level of detail that leads to conclusions somewhat different from those made earlier.

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