Panorama of Nodal Superconductors

TL;DR

This paper reviews the discovery and analysis of various unconventional and nodal superconductors, emphasizing the importance of symmetry determination of their order parameters using angular-controlled thermal conductivity measurements.

Contribution

It highlights the use of angular-controlled thermal conductivity in vortex states as a key method for identifying the gap symmetry in multiple nodal superconductors.

Findings

Identified gap symmetries in Sr2RuO4, CeCoIn5, and others.

Demonstrated the effectiveness of thermal conductivity measurements in superconductor analysis.

Provided a comprehensive overview of nodal superconductor classes.

Abstract

Since 1979, many new classes of superconductors have been discovered, including heavy-fermion compounds, organic conductors, high-Tc cuprates, and Sr2RuO4. Most of these superconductors are unconventional and/or nodal. Therefore it is of central importance to determine the symmetry of the order parameter in each of these superconductors. In particular, the angular-controlled thermal conductivity in the vortex state provides a unique means of investigating the nodal structure of the superconducting energy gap when high-quality single crystals in the extremely clean limit are available. Using this method, Izawa et al have recently succeeded in identifying the energy gap symmetry of superconductivity in Sr2RuO4, CeCoIn5, kappa-(ET)2Cu(NCS)2, YNi2B2C, and PrOs4Sb12.