Possible spin triplet superconductivity in Na$_x$CoO$_{2}\cdot y$H$_{2}$0

TL;DR

This paper proposes that Na$_x$CoO$_{2} imes y$H$_2$O may host a novel spin-triplet superconductivity driven by antiferromagnetic fluctuations, with a pairing mechanism similar to Sr$_{2}$RuO$_4$ but enhanced by its hexagonal Fermi-surface.

Contribution

The authors suggest a new spin-triplet superconductivity mechanism in Na$_x$CoO$_{2} imes y$H$_2$O based on symmetry and experimental insights, extending beyond previous RVB-based theories.

Findings

Possible realization of spin-triplet pairing in Na$_x$CoO$_{2} imes y$H$_2$O

Enhanced pairing tendency due to hexagonal Fermi-surface structure

Comparison with Sr$_{2}$RuO$_4$ pairing mechanism

Abstract

Combining symmetry based considerations with inputs from available experimental results, we make the case that a novel spin-triplet superconductivity triggered by antiferromagnetic fluctuations may be realized in the newly discovered layered cobaltide Na$_x$CoO$_{2}\cdot y$H$_2$O. In the proposed picture, unaccessable via resonating-valence-bond physics extrapolated from half-filling, the pairing process is similar to that advanced for Sr$_{2}$RuO$_4$, but enjoys a further advantage coming from the hexagonal structure of the Fermi-surface which gives a stronger pairing tendency.