Is Sr2RuO4 a triplet superconductor?

TL;DR

This paper investigates the magnetic field dependence of specific heat in Sr2RuO4, suggesting it could be a singlet superconductor or a triplet with a basal-plane d-vector, based on microscopic calculations including Pauli effects.

Contribution

It provides a microscopic analysis of specific heat behavior in Sr2RuO4 considering Pauli paramagnetic effects, offering insights into its pairing symmetry.

Findings

Systematic b3(H) behaviors explained by Pauli effects

Magnetization data consistent with the model

Supports singlet or basal-plane triplet pairing hypothesis

Abstract

The field dependence of the specific heat \gamma(H) at lower temperatures in Sr2RuO4 is analyzed by solving microscopic Eilenberger equation numerically. We find that systematic \gamma(H) behaviors from a concaved \sqrt H to a convex H^{\alpha} (\alpha>1) under H orientation change are understood by taking account of the Pauli paramagnetic effect. The magnetizations are shown to be consistent with it. This implies either a singlet pairing or a triplet one with d-vector locked in the basal plane, which allows us to explain other mysteries of this compound in a consistent way.