Comparison of superconductivity in Sr_2RuO_4 and copper oxides

TL;DR

This paper compares superconductivity in Sr_2RuO_4 and copper oxides using a t-J-I model, highlighting how different magnetic fluctuations influence pairing symmetry and critical temperatures.

Contribution

It introduces a unified model to explain the contrasting superconducting states and transition temperatures in ruthenates and cuprates based on magnetic interactions.

Findings

Antiferromagnetic coupling leads to d_{x^2-y^2} symmetry and higher T_c in cuprates.

Ferromagnetic coupling results in spin-triplet p-wave pairing and lower T_c in Sr_2RuO_4.

Gap anisotropy differences explain the large T_c disparity.

Abstract

To compare the superconductivity in strongly correlated electron systems with the antiferromagnetic fluctuations in the copper oxides and with the ferromagnetic fluctuations in Sr_2RuO_4 a t-J-I model is proposed. The antiferromagnetic coupling J results in the superconducting state of d_{x^2-y^2} symmetry and the ferromagnetic coupling constant I results in the spin-triplet p-type state. The difference in the gap anisotropies provides the large difference in T_c values, for the typical values of the coupling constants: T_c of order of 1K for the ruthenate and T_c of order of 100K for the cuprates.