Regensburg 2000 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 17: Postersitzung II: Pinning und Vortexdynamik (1-8), Supraleitung: Theorie (9-13), Korrelierte Elektronen (14-48), Niederdimensionale Systeme (49-68), Quantenflüssigkeiten (69-75)

TT 17.9: Poster

Mittwoch, 29. März 2000, 14:30–18:00, A

Relationship between incommensurability and superconductivity in charge-density wave systems — •G. Seibold and S. Varlamov — Lehrstuhl Theoretische Physik, BTU Cottbus, 03013 Cottbus, Germany

We study the pairing potential induced by fluctuations around a charge-density wave (CDW) with scattering vector Q by means of the Fröhlich transformation. For general commensurability M, defined as |k+MQ⟩=|k⟩, we find that the intraband pair scattering within the M subbands scales with M whereas the interband pair scattering becomes suppressed with increasing CDW order parameter. As a consequence superconductivity is suppressed when the Fermi energy is located between the subbands as it is usually the case for nesting induced CDW’s, but due to the vertex renormalization it can be substantially enhanced when the chemical potential is shifted sufficiently inside one of the subbands. The model can help to understand the experimentally observed dependence of the superconducting transition temperature from the stripe phase incommensurability in the lanthanum cuprates.