Temporal universal conductance fluctuations in RuO$_2$ nanowires due to mobile defects

TL;DR

This study reports the observation of temporal universal conductance fluctuations in RuO$_2$ nanowires at cryogenic temperatures, revealing insights into electron scattering by mobile defects and their characteristic time scales.

Contribution

It demonstrates the presence of TUCF in RuO$_2$ nanowires and analyzes their origin, magnitude, and relation to mobile defect dynamics, expanding understanding of mesoscopic fluctuations in metal oxide nanostructures.

Findings

TUCF observed up to 10 K temperature.

Root-mean-square fluctuations reach ~0.2 e^2/h at low T.

Fluctuations linked to mobile defect scattering.

Abstract

Temporal universal conductance fluctuations (TUCF) are observed in RuO$_2$ nanowires at cryogenic temperatures. The fluctuations persist up to very high $T \sim 10$ K. Their root-mean-square magnitudes increase with decreasing $T$, reaching $\sim 0.2 e^2/h$ at $T \lesssim 2$ K. These fluctuations are shown to originate from scattering of conduction electrons with rich amounts of mobile defects in artificially synthesized metal oxide nanowires. TUCF characteristics in both one-dimensional saturated and unsaturated regimes are identified and explained in terms of current theories. Furthermore, the TUCF as a probe for the characteristic time scales of the mobile defects (two-level systems) are discussed.