Hidden one-dimensional electronic structure and non-Fermi liquid angle resolved photoemission line shapes of $\eta$-Mo$_4$O$_{11}$

TL;DR

This study uses ARPES to reveal the hidden one-dimensional electronic structure and non-Fermi liquid behavior in $ ext{η}$-Mo$_4$O$_{11}$, a layered metal with charge density wave transitions, providing insights into its complex electronic properties.

Contribution

First direct observation of the hidden-1d Fermi surface and anisotropic gap in $ ext{η}$-Mo$_4$O$_{11}$, linking experimental ARPES data with theoretical CDW models.

Findings

Observation of hidden-1d Fermi surface

Anisotropic gap opening at 109 K transition

ARPES line shape anomalies indicating non-Fermi liquid physics

Abstract

We report angle resolved photoemission (ARPES) spectra of $\eta$-Mo$_4$O$_{11}$, a layered metal that undergoes two charge density wave (CDW) transitions at 109 K and 30 K. We have directly observed the ``hidden one-dimensional (hidden-1d)'' Fermi surface and an anisotropic gap opening associated with the 109 K transition, in agreement with the band theoretical description of the CDW transition. In addition, as in other hidden-1d materials such as NaMo$_6$O$_{17}$, the ARPES line shapes show certain anomalies, which we discuss in terms of non-Fermi liquid physics and possible roles of disorder.