Orbital Fluctuation-Induced Triplet Superconductivity : Mechanism of Superconductivity in ${\rm Sr}_{2}{\rm RuO}_{4}$

TL;DR

This paper proposes that orbital fluctuations in a degenerate Hubbard model induce triplet superconductivity in Sr2RuO4, especially near orbital instability, highlighting a mechanism specific to orbitally degenerate systems with multiple Fermi surfaces.

Contribution

It introduces a novel mechanism for triplet superconductivity driven by orbital fluctuations in orbitally degenerate systems, analyzed within weak coupling theory.

Findings

Triplet superconductivity emerges near orbital instability.

Orbital fluctuations are key to the superconducting mechanism.

Applicable to systems with multiple Fermi surfaces.

Abstract

The mechanism of superconductivity in ${\rm Sr}_{2}{\rm RuO}_{4}$ is studied using a degenerate Hubbard model within the weak coupling theory. When the system approaches the orbital instability which is realized due to increasing the on-site Coulomb interaction between the electrons in the different orbitals, it is shown that the triplet superconductivity appears. This superconducting mechanism is only available in orbitally degenerate systems with multiple Fermi surfaces.