### Abstract

The most popular description of superconductivity phenomenon in Sr_{2}RuO_{4} is based on a so-called single-band (usually γ-band) "isotropic p-wave order parameter". In a magnetic field parallel to the conducting planes, such triplet "isotropic p-wave phase" is not destroyed by the Clogston-Chandrasekhar paramagnetic limiting field and can be destroyed only by the Meissner currents (i.e., the orbital effects). We analyze the orbital destructive effects against superconductivity for in-plane magnetic field (when electron orbits are open) and find that H_{c2}^{∥}(0) ≃ 0.75 T_{c}(dH_{c2}^{∥}(T)/dT)_{Tc} (which is a little bigger than the Werthamer-Helfand-Hohenberg value for an isotropic 3D case). We point out that the experimentally determined ratio H_{c2}^{∥}(0)/T_{c}(dH_{c2} ^{∥}(T)/dT)T_{c} ≃ 0.44 - 0.5 in Sr_{2}RuO_{4} is significantly less than the calculated value 0.75. Since the upper critical field, K_{c2}^{∥}(T). is a well experimentally defined quantity in Sr_{2}RuO_{4} (unlike high-T_{c} superconductors) we conclude that the single-band triplet "isotropic p-wave order parameter" seems to be inappropriate description of superconductivity in this material. Two possibilities are discussed: 1) Three-band nature of triplet superconductivity; 2) Singlet (d-wave) nature of superconducting pairing (in this case, the destructive actions of both the orbital effects and the Clogston-Chandrasekhar paramagnetic effects result in an agreement with the experimentally observed value of H_{c2}^{∥}(0)/T_{c}(dH_{c2} ^{∥}(T)/dT)_{Tc}).

Original language | English (US) |
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Pages (from-to) | 1677-1678 |

Number of pages | 2 |

Journal | Physica C: Superconductivity and its applications |

Volume | 341-348 |

Issue number | PART 2 |

DOIs | |

State | Published - Jan 1 2000 |

Externally published | Yes |

### ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering