Destruction of the small Fermi surfaces in Na$_x$CoO$_2$ by Na disorder

TL;DR

This study demonstrates through density functional calculations that Na disorder in Na$_x$CoO$_2$ destroys small $e_g'$ Fermi surfaces, explaining their absence in experiments and resolving previous theoretical-experimental discrepancies.

Contribution

It reveals that Na disorder eliminates small Fermi surfaces in Na$_x$CoO$_2$, clarifying the mismatch between band structure predictions and photoemission observations.

Findings

Na disorder destroys small $e_g'$ Fermi surfaces

Provides explanation for non-observation in experiments

Resolves discrepancy between theory and experiment

Abstract

We show using density functional calculations that the small $e_g'$ Fermi surfaces in Na$_x$CoO$_2$ are destroyed by Na disorder. This provides a means to resolve the prediction of these sections in band structure calculations with their non-observation in angle resolved photoemission experiments.