On the low temperature properties and specific anisotropy of pure anisotropically paired superconductors

TL;DR

This paper investigates the low temperature properties and anisotropy of pure unconventional superconductors, focusing on how the momentum dependence of the order parameter influences physical quantities and experimental identification of pairing types.

Contribution

It analyzes the effects of order parameter node multiplicities and symmetry on low temperature behaviors and boundary conditions in unconventional superconductors.

Findings

Different multiplicities of order parameter nodes affect physical quantities.

Anisotropy influences low temperature behaviors of specific heat, penetration depth, and thermal conductivity.

Boundary conditions near Tc exhibit specific anisotropic features for unconventional pairing.

Abstract

Dependences of low temperature behavior and 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. A 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. 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, the I-V curves of SS and NS tunnel junctions at low voltages are examined. A specific anisotropy of the boundary conditions for unconventional superconducting order parameter near $T_c$ for the case of specular reflection from the boundary is also investigated.