Temporal universal conductance fluctuations in RuO2 nanowires due to mobile defects

Abstract

Temporal universal conductance fluctuations (TUCF's) are observed in RuO2 nanowires at cryogenic temperatures. The fluctuations persist up to very high T similar to 10 K. Their root-mean-square magnitudes increase with decreasing T, reaching similar to 0.2e(2)/h at T less than or similar to 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's as a probe for the characteristic time scales of the mobile defects (two-level systems) are discussed.