## Abstract

From the BCS theory, we derive an equation determining the upper critical field, H_{c2}(T), parallel to conducting planes of both layered Q2D and Q1D superconductors. It extends the quasiclassical Ginzburg-Landau-Abrikosov- Gor'kov (GLAG) and Lawrence-Doniach descriptions of H_{c2}(T) to the case of high magnetic fields where the quantum nature of an electron motion along open Fermi surfaces is important. This equation demonstrates two new phenomena: (1) a complete restoration of superconductivity at H ≃ H _{c5} > H_{c2}(0) in the case of p-wave pairing of electrons; (2) a surviving of superconductivity at H_{c2}(0) < H < H _{p}* in the case of s(d)-wave pairing, where H_{p}* ≠ H_{p} [Here, H_{c2}(0) and H_{p} are the quasiclassical GLAG upper critical field and the paramagnetic Clogston-Chandrasekhar limiting field, correspondingly; H_{c5} and H_{p}* are defined in the text]. Our analysis of recent experimental data on (TMTSF)_{2}PF_{6} by I. J. Lee et al. and M. J. Naughton et al. shows that superconductivity significantly exceeds H _{p}*. This demonstrates a strong suppression of the Pauli pair-breaking effects and may reflect a p-wave pairing of electrons. We propose to measure H_{c2}(T) in Sr_{2}RuO_{4} (which is believed to be a p-wave superconductor) to prove a symmetry of a superconducting order parameter.

Original language | English (US) |
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Pages (from-to) | 453-458 |

Number of pages | 6 |

Journal | Journal of Superconductivity and Novel Magnetism |

Volume | 12 |

Issue number | 3 |

State | Published - Dec 1 1999 |

Externally published | Yes |

## Keywords

- High-T
- Organic superconductors
- P-wave pairing of electrons
- Reentrant superconductivity
- Superconducting gap symmetry
- Superconductors

## ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics