Orbital dependent superconductivity in Sr_2RuO_4

TL;DR

This paper reveals that in Sr_2RuO_4, different orbital characters on the Fermi surface exhibit weak coupling in superconductivity, resulting in two energy scales and unique low-temperature thermodynamic and transport behaviors.

Contribution

It introduces the concept of orbital-dependent pairing in Sr_2RuO_4, explaining observed anomalies through weak coupling between different orbital states.

Findings

Two disparate energy scales in superconducting state

Weak coupling between Ru 4d-xy and Ru 4d-xz/yz orbitals

Explanation for residual density of states in experiments

Abstract

We show that for superconducting Sr_2RuO_4 any unconventional pairing in the part of the Fermi surface with Ru 4d-xy orbital character is weakly coupled to that with Ru 4d-xz, 4d-yz orbital character. This naturally gives rise to two disparate energy scales in the superconducting state which leads to novel low temperature properties in a variety of thermodynamic and transport properties and which would also account for the large residual density of states seen in specific heat and NQR measurements.