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Antiferromagéntisme et supraconductivité dans les conducteurs quasi-unidimensionnels, étude par renormalisation

Abstract : We study antiferromagnetism and superconductivity in quasi-one-dimensional Fermi systems. We start from a two-dimensional anisotropic Hubbard model. The phase diagram is established using the functional renormalization group. We obtain a crossover from a one-dimensional regime at high temperature to a two-dimensional regime at low temperature. Within the latter, spin and charge fluctuations can stabilize the following phases, depending on the nesting of the Fermi surface and the effective range of electron-electron interactions: Antiferromagnetism, singlet d-wave superconductivity, triplet f-wave superconductivity, or a charge density wave. These results are compared to experiments on the organic conductors (TMTSF)_2X (the Bechgaard salts). Recent experiments on these materials could indicate the existence of triplet superconductivity next to the antiferromagnetic phase. We also study the effect of an additional potential with double periodicity in a direction perpendicular to that of maximum conductivity. Such a potential is present in (TMTSF)_2ClO_4. In this case, there are two bands at the Fermi level. Several Fourier components of the spin fluctuations compete, and some of them are coupled. The same applies to the superconducting fluctuations. The resulting phase diagram is very rich. It contains two antiferromagnetic and two superconducting phases, one being predominantly d-wave and the other predominantly g-wave.
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https://tel.archives-ouvertes.fr/tel-00007189
Contributor : Jan Christoph Nickel <>
Submitted on : Friday, October 22, 2004 - 8:53:58 PM
Last modification on : Wednesday, September 16, 2020 - 4:32:00 PM
Long-term archiving on: : Friday, April 2, 2010 - 9:08:55 PM

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  • HAL Id : tel-00007189, version 1

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Jan Christoph Nickel. Antiferromagéntisme et supraconductivité dans les conducteurs quasi-unidimensionnels, étude par renormalisation. Supraconductivité [cond-mat.supr-con]. Université Paris Sud - Paris XI, 2004. Français. ⟨tel-00007189v1⟩

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