Angle-resolved photoemission study of quasi-one-dimensional superconductor $\beta$-Na$_{0.33}$V$_2$O$_5$

TL;DR

This study uses angle-resolved photoemission spectroscopy to investigate the electronic structure of the quasi-one-dimensional superconductor $eta$-Na$_{0.33}$V$_2$O$_5$, revealing band dispersions along the chain direction and strong electron-phonon coupling effects.

Contribution

First detailed ARPES analysis of $eta$-Na$_{0.33}$V$_2$O$_5$, demonstrating its quasi-1D electronic structure and polaronic features related to electron-phonon interactions.

Findings

Band dispersions observed only along the chain direction.

V 3d spectra show a broad feature at ~1 eV below $E_F$.

Spectral intensity peaks at $k \, ext{~} \, ext{±} \, rac{\pi}{4b}$.

Abstract

We have studied the electronic structure of $\beta$-Na$_{0.33}$V$_2$O$_5$, which becomes a superconductor under pressure, by angle-resolved photoemission spectroscopy. Clear band dispersions is observed only along the chain direction, indicating the quasi-one-dimensional (1D) electronic structure. The spectra of the V 3d band are dominated by a Gaussian-like broad feature at $\sim$ 1 eV below the Fermi level ($E_F$) with negligible intensity at $E_F$, which we attribute to strong electron-phonon coupling as in other 1D polaronic metals. In the momentum space, the spectra show a maximum intensity at $k \sim \pm \pi/4b$, where $b$ is the V-V distance along the b-axis, reflecting the band filling of the chain and/or ladder.