Weak coupling instabilities of two-dimensional lattice electrons
- Binz, Benedikt Department of Physics, University of Fribourg, Switzerland - Theoretische Physik, ETH Zürich, Switzerland
- Baeriswyl, Dionys Department of Physics, University of Fribourg, Switzerland
- Douçot, B. Laboratoire de Physique Théorique et Hautes Energies, CNRS Universités Paris VII, France
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10.05.2004
Published in:
- Physica C: Superconductivity. - 2004, vol. 408-410, p. 250-251
English
We present a consistent and systematic study of a two-dimensional extended Hubbard model in the weak coupling limit. Quite generally, the electron gas is unstable towards a superconducting state even in the absence of phonons, since high-energy spin fluctuations create an effective attraction between the quasi-particles. However in the special case of a half-filled nearest-neighbor tight-binding band, the Fermi surface is nested and the system is at a Van Hove singularity. In this situation, there are six competing instabilities: s- and d-wave superconductivity, spin- and charge-density waves and two phases with circulating charge and spin currents, respectively. The required renormalization group formalism can be presented on a most elementary level, connecting the idea of the "parquet summation" to the more modern concept of Wilson's effective action. As a result, a rich phase diagram is obtained as a function of the model interaction. We also argue that the one-loop approximation is insufficient in a case where the Fermi surface is at a Van Hove singularity but not nested.
- Faculty
- Faculté des sciences et de médecine
- Department
- Département de Physique
- Language
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- English
- Classification
- Physics
- License
- License undefined
- Identifiers
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- RERO DOC 4278
- DOI 10.1016/j.physc.2004.02.145
- Persistent URL
- https://folia.unifr.ch/unifr/documents/299561
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