Theory of Transport Properties in the p-wave Superconducting State of Sr2RuO4 - A Microscopic Determination of the Gap Structure -

TL;DR

This paper presents a microscopic analysis of transport properties in Sr2RuO4's p-wave superconducting state, revealing nodal structures and explaining experimental observations of thermal conductivity and ultrasound attenuation.

Contribution

It introduces a detailed microscopic calculation of gap structure and transport coefficients in Sr2RuO4, incorporating realistic electronic structure and impurity effects.

Findings

Nodal structures exist along the c-axis in Sr2RuO4.

Thermal excitations on passive bands significantly affect thermal conductivity.

Transport coefficients match experimental temperature dependence.

Abstract

We provide a detailed quantitative analysis of transport properties in the p-wave superconducting state of Sr2RuO4. Specifically, we calculate ultrasound attenuation rate and electronic thermal conductivity within the mean field approximation. The impurity scattering of the quasi-particles are treated within the self-consistent T-matrix approximation, and assumed to be in the unitarity limit. The momentum dependence of the gap function is determined by solving the Eliashberg equation for a three-band Hubbard model with the realistic electronic structure of Sr2RuO4. On the basis of the microscopic theory, we can naturally expect nodal structures along the c-axis on the cylindrical Fermi surfaces, even if we assume the chiral pairing state (i.e., \Delta(k) \sim k_x \pm {\rm i} k_y). Consequently, we obtain the temperature dependence of the transport coefficients in agreement with the experimental results. We can clarify that actually the thermal excitations on the passively superconducting bands contribute significantly to the thermal conductivity in a wide temperature range, in contrast to the case of other physical quantities.