Evidence for Bose liquid from anomalous shot noise in nanojunctions of bad metal beta-Ta

TL;DR

This study observes anomalous shot noise in beta-tantalum nanojunctions, indicating the presence of a correlated charge liquid, which challenges traditional Fermi liquid theory and suggests new electron correlation phenomena.

Contribution

The paper provides experimental evidence of non-Fermi liquid behavior in beta-tantalum, revealing a potential Bose liquid state through shot noise analysis and supporting data from spectroscopy and calculations.

Findings

Fano factors cluster around even multiples of Fermi liquid values

Magnetic impurities influence shot noise behavior

Reduced density of states near Fermi level observed

Abstract

We report anomalous shot noise in nanojunctions of beta-tantalum, a ``bad" metal whose electronic properties are inconsistent with the Fermi liquid theory. Fano factors cluster around even multiples of the values expected for Fermi liquids, suggesting that beta-Ta may host a correlated charge liquid of Cooper pair-like electron groups. Further evidence for correlations is provided by the effects of magnetic impurities, as well as reduced density of states near the Fermi level indicated by point contact spectroscopy and first principles calculations. Our results open new avenues for studies and applications of electron correlations.