Hamburg 2001 – scientific programme

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TT: Tiefe Temperaturen

TT 18: Niederdimensionale Systeme, Magnetotransport, Quantenhalleffekt I

TT 18.3: Talk

Wednesday, March 28, 2001, 16:15–16:30, A

Electronic Structure of Solids with Competing Periodic Potentials — •Johannes Voit — Universität Bayreuth

We investigate the distribution of spectral weight of 1D electrons in commensurate and incommensurate superlattices. When the superlattice is commensurate, the spectral weight is not periodic in k-space despite a periodic crystal structure. It is concentrated on the extended zone scheme dispersion and has shadow bands in the periodic zone scheme. When electrons are subject to a potential with two incommensurate periods, translational invariance is lost, and no periodic band structure is expected. However, we find that the spectral function does show dispersing band states with signatures of both periodicities. Apparent band structures and pronounced shadow bands are generated by the nonuniform distribution of electronic spectral weight over the complex eigenvalue spectrum. Comparison with experiments on the 1D Peierls system (TaSe₄)₂I suggest that this material should be described as a weakly doped Peierls ladder where the incommensurate superlattice potentials couple to the two ladder bands separately.