Shubnikov de Haas effect in the metallic state of Na$_{0.3}$CoO$_2$

TL;DR

This paper reports the observation of Shubnikov de Haas oscillations in Na$_{0.3}$CoO$_2$, revealing details about its Fermi surface and suggesting possible reconstructions or pockets, with implications for understanding its metallic state.

Contribution

The study provides the first clear observation of Shubnikov de Haas oscillations in Na$_{0.3}$CoO$_2$, linking Fermi surface features to Na superstructures and discussing their implications.

Findings

Detected two oscillation frequencies corresponding to specific Fermi surface areas.

Suggests Fermi surface reconstruction due to Na superstructures.

Incompatible with the existence of $ ext{ε}_g^ extprime$ pockets based on specific heat data.

Abstract

Shubnikov de Haas oscillations for two well defined frequencies, corresponding respectively to areas of 0.8 and 1.36% of the first Brillouin zone (FBZ), were observed in single crystals of Na$_{0.3}$CoO$_2$. The existence of Na superstructures in Na$_{0.3}$CoO$_2$, coupled with this observation, suggests the possibility that the periods are due to the reconstruction of the large Fermi surface around the $\Gamma$ point. An alternative interpretation in terms of the long sought-after $\epsilon_g^\prime$ pockets is also considered but found to be incompatible with existing specific heat data.