Observation of conductance fluctuations in largeIn2O3−xfilms

We have measured the magnetoconductance in the hopping regime of two thin films of crystalline ${\mathrm{In}}_2$ ${\mathrm{O}}_{3\mathrm{-}\mathit{x}}$. The films are 18 nm thick and have large (macroscopic) areas 2×2 and 1×0.3 ${\mathrm{mm}}^2$. We observe a large positive magnetoconductance and reproducible conductance fluctuations. The conductance fluctuations are easy to observe below 100 mK and their amplitude is consistent with simple ensemble averaging of phase-coherent regions. When the field is rotated into the plane of the film, the field scale for the conductance fluctuations increases by a factor of 2 suggesting that they are partly due to orbital effects.