Theoretical Analysis of the Symmetry of the Order Parameter in Unconventional Superconductors: Singlet Versus Triplet Pairing

  • D. Manske
  • I. Eremin
  • K. H. Bennemann
Part of the NATO Science Series book series (NAII, volume 67)

Abstract

The novel superconductivity with Tc ≈ 1.5K observed recently in layered Sr2RuO4 seems to be a new example of unconventional superconductivity [1]. Its structure is isomorphic to the high-Tc cuprate family La2-x ;Sr x CuO4 which, however, has a Tc ≈ 30K and is a singulet (but unconventional) superconductor. This makes the theoretical comparison of ruthenates and high-Tc cuprates very interesting. In Sr2RuO4 the presence of incommensurate antiferromagnetic and ferromagnetic spin fluctuations has been confirmed recently by inelastic neutron scattering (INS) [2] and NMR 17O Knight shift [3], respectively, suggesting also a pairing mechanism for Cooper-pairs due to spin fluctuations like in cuprates. This is further supported by the observed non s-wave symmetry of the order parameter. In contrast to cuprates, NMR [4] and polarized neutron scattering [5] measurements indicate spin-triplet state Cooper-pairing. In analogy to 3He this led theorists to conclude that p-wave superconductivity is present [6]. However, by fitting the specific heat and the ultrasound attenuation Maki and co-workers doubted p-wave superconductivity [7] and propose an f-wave symmetry of the superconducting order parameter. A similar conclusion was drawn in Ref. [8]. Recently it has been reported that also thermal conductivity measurements are most consistent with f-wave symmetry [9].

Keywords

Anisotropy Attenuation Eter Perovskite Hunt 

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Copyright information

© Springer Science+Business Media Dordrecht 2002

Authors and Affiliations

  • D. Manske
    • 1
  • I. Eremin
    • 1
    • 2
  • K. H. Bennemann
    • 1
  1. 1.Institut für Theoretische PhysikFreie Universität BerlinBerlinGermany
  2. 2.Physics DepartmentKazan State UniversityKazanRussia

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