Low-temperature properties and specific anisotropy of pure anisotropically paired superconductors

Dependences of low-temperature behavior and the anisotropy of various physical quantities for pure unconventional superconductors upon a particular form of momentum direction dependence for the superconducting order parameter (within the framework of the same symmetry type of superconducting pairing) are considered. Special attention is drawn to the possibility of different multiplicities of the nodes of the order parameter under their fixed positions on the Fermi surface, which are governed by symmetry. The problem of an unambiguous identification of a type of superconducting pairing on the basis of corresponding experimental results is discussed. The quasiparticle density of states at low energy for both homogeneous and mixed states, the low-temperature dependences of the specific heat, penetration depth, and thermal conductivity, and the I-V curves of superconductor-superconductor and normal-metal–superconductor tunnel junctions at low voltages are examined. A specific anisotropy of the boundary conditions for unconventional superconducting order parameters near ${\mathit{T}}_{\mathit{c}}$ for the case of specular reflection from the boundary is also investigated. © 1996 The American Physical Society.