Effects of Strong Magnetic Fields on Pairing Fluctuations in
High Temperature Superconductors

Author: Matthias Eschrig, D. Rainer and J. A. Sauls
Comments: 21 pages with 22 figures
Journals: Physical Review B 59, 12095 (1999) [DOI] [PDF]

We present the theory for the effects of superconducting pairing fluctuations on the nuclear spin-lattice relaxation rate, 1/T1, and the NMR Knight shift for layered superconductors in high magnetic fields. These results can be used to clarify the origin of the pseudogap in high-Tc, cuprates, which has been attributed to spin fluctuations as well as pairing fluctuations. We present theoretical results for s-wave and d-wave pairing fluctuations and show that recent experiments in optimally doped YBa2Cu3O{7-d} are described by d-wave pairing fluctuations. In addition, we show that the orthorhombic distortion in YBa2Cu3O{7-d} accounts for an experimentally observed discrepancy between 1/T1 obtained by NQR and NMR at low field. We propose an NMR experiment to distinguish a fluctuating s-wave order parameter from a fluctuating strongly anisotropic order parameter, which may be applied to the system Nd2-xCexCuO{4-d} and possibly other layered superconductors.

[PDF] [arXiv]

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