ELECTRONIC STRUCTURE OF TWO-DIMENSIONAL HEXAGONAL DISELENIDES: CHARGE DENSITY WAVES AND PSEUDOGAP BEHAVIOR
Kuchinskii E.Z., Nekrasov I.A., Sadovskii M.V.

Received: June 27, 2011

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We theoretically study the electronic structure (spectral functions and Fermi surfaces) of incommensurate pseudogap and charge density wave (CDW) and commensurate CDW phases of quasi-two-dimensional diselenides 2H-TaSe₂ and 2H-NbSe₂. The incommensurate pseudogap regime is described within the scenario based on short-range-order CDW fluctuations, considered within the static Gaussian random field model. In contrast, e. g., to high-T_c cuprates, layered dichalcogenides have several different CDW scattering vectors and an electronic spectrum with two bands at the Fermi level. For this, we present a theoretical background for the description of multiple scattering processes within a multiple-band electronic spectrum. Theoretical spectral functions and Fermi surfaces thus obtained are compared with recent ARPES experimental data, demonstrating rather good qualitative agreement.