Anomalous thermodynamic power laws near topological transitions in nodal superconductors

TL;DR

This paper reveals new types of nodal structures in unconventional superconductors that lead to anomalous thermodynamic power laws, especially near topological transitions, with potential experimental observations in specific materials.

Contribution

It introduces a broader class of nodal types occurring at topological transitions and links them to unique thermodynamic power laws in superconductors.

Findings

Identification of new nodal types at topological transitions

Derivation of anomalous non-integer thermodynamic power laws

Potential experimental observation in Li₂Pd₃₋ₓPtₓB

Abstract

Unconventional superconductors are most frequently identified by the observation of power-law behaviour on low-temperature thermodynamic or transport properties, such as specific heat. Here we show that, in addition to the usual point and line nodes, a much wider class of different nodal types can occur. These new types of nodes typically occur when there are transitions between different types of gap node topology, for example when point or line nodes first appear as a function of some physical parameter. We identify anomalous, non-integer thermodynamic power laws associated with these new nodal types, and give physical examples of superconductors in which they might be observed experimentally, including the noncentrosymmetric superconductor Li$_2$Pd$_{3-x}$Pt$_x$B.