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PRB.103.195150 Nei Lopes

Interplay between charge density wave and superconductivity in multiband systems with interband Coulomb interaction

Phys. Rev. B 103, 195150

Keywords

Idea of the paper

To investigate the interplay between CDW and SC orders in a square lattice two-band model.

Summary

  • The bands have different effective masses and the CDW phase arises from interband Coulomb correlations. On the other hand, the SC is due to a local intraband attractive interaction.
  • intermetallic compounds and their alloys , like the layered SCs SrPt2As2 and LaPt2Si2. These systems have in common a rather narrow d-band with moderate electronic correlations (as compared with the f -bands in heavy fermions, where a large U approach is necessary ) coexisting with large sp-bands
  • Solved using HF mean field theory. Nambu’s spinor representation to write the Hamiltonian in matrix form. Eigenvalues are obtained numerically and free energy density is minimized with respect to the relevant variables to obtain the phase diagrams as functions of parameters, such as the strength of the CDW and SC interactions, hybridization, total number of particles, and relative depth of the bands.
  • Result : There is an intrinsic competition between CDW and SC orders, but depending on the parameters of the model these phases may coexist.