Long electron dephasing length and disorder-induced spin-orbit coupling in indium tin oxide nanowires

Abstract

We have measured the quantum-interference magnetoresistances in two single indium tin oxide (ITO) nanowires between 0.25 and 40 K, by using the four-probe configuration method. The magnetoresistances are compared with the one-dimensional weak-(anti)localization theory to extract the electron dephasing length ${L}_{\ensuremath{\varphi}}$. We found, in a 60-nm-diameter nanowire with a low resistivity of $\ensuremath{\rho}(10\text{ }\text{K})=185\text{ }\ensuremath{\mu}\ensuremath{\Omega}\text{ }\text{cm}$, that ${L}_{\ensuremath{\varphi}}$ is long, increasing from 150 nm at 40 K to 520 nm at 0.25 K. Therefore, the nanowire reveals strict one-dimensional weak-localization effect up to several tens of degrees of kelvin. In a second 72-nm-diameter nanowire with a high resistivity of $\ensuremath{\rho}(10\text{ }\text{K})=1030\text{ }\ensuremath{\mu}\ensuremath{\Omega}\text{ }\text{cm}$, the dephasing length is suppressed to ${L}_{\ensuremath{\varphi}}(0.26\text{ }\text{K})=200\text{ }\text{nm}$, and thus a crossover of the effective device dimensionality from one to three occurs at about 12 K. In particular, disorder-induced spin-orbit coupling is evident in the latter sample, manifesting weak-antilocalization effect at temperatures below $\ensuremath{\sim}4\text{ }\text{K}$. These observations demonstrate that versatile quantum-interference effects can be realized in ITO nanowires by controlling differing levels of atomic defects and impurities.