Unconventional Pairing in Heavy Fermion Metals

Abstract

The Fermi-liquid theory of superconductivity is applicable to a broad range of systems that are candidates for unconventional pairing. Fundamental differences between unconventional and conventional anisotropic superconductors are illustrated by the unique effects that impurities have on the low-temperature transport properties of unconventional superconductors. For special classes of unconventional superconductors the low-temperature transport coefficients are {\it universal}, i.e. independent of the impurity concentration and scattering phase shift. The existence of a universal limit depends on the symmetry of the order parameter and is achieved at low temperatures $k_{B}T\ll \gamma \ll {\Delta }_0$, where $\gamma$ is the bandwidth of the impurity induced Andreev bound states. In the case of UPt${}_3$ thermal conductivity measurements favor an $E_{1g}$ or $E_{2u}$ ground state. Measurements at ultra-low temperatures should distinguish different pairing states.

8 pages in a LaTex (3.0) file plus 5 Figures in PostScript. To appear in the Proceedings of the XXI International Conference on Low Temperature Physics held in Prague, 8-14 August 1996

References in corpus (7)

• The Order Parameter for the Superconducting Phases of UPt${}_3$
• Electronic thermal conductivity and the Wiedemann-Franz law for unconventional superconductors
• The Effect of Surfaces on the Tunneling Density of States of an Anisotropically Paired Superconductor
• Infrared Conductivity in Layered $d$-wave Superconductors
• Thermal Conductivity of Superconducting UPt${}_3$ at Low Temperatures
• $E_{1g}$ model of superconducting UPt${}_3$
• Strong Coupling Theory of Superconductivity