Spin-orbit induced mixed-parity pairing in Sr$_2$RuO$_4$: a quantum many-body calculation

TL;DR

This study employs a quantum many-body approach with realistic parameters to model Sr$_2$RuO$_4$, revealing a predominantly even-parity superconducting state with a spin-orbit induced odd-parity component, aligning better with experimental observations.

Contribution

It introduces a self-consistent quantum many-body calculation that captures mixed-parity pairing in Sr$_2$RuO$_4$, advancing understanding of its superconducting state.

Findings

Dominant even-parity superconducting component

Induced odd-parity component due to spin-orbit coupling

Enhanced agreement with experimental properties

Abstract

The unusual superconducting state in Sr$_2$RuO$_4$ has long been viewed as being analogous to a superfluid state in liquid $^3$He. Nevertheless, calculations based on this odd-parity state are presently unable to completely reconcile the properties of Sr$_2$RuO$_4$. Using a self-consistent quantum many-body scheme that employs realistic parameters, we are able to model several signature properties of the normal and superconducting states of Sr$_2$RuO$_4$. We find that the dominant component of the model superconducting state is of even parity and closely related to superconducting state for the high-$T_c$ cuprates although a smaller odd-parity component is induced by spin-orbit coupling. This mixed pairing state gives a more complete representation of the complex phenomena measured in Sr$_2$RuO$_4$.