Observation of a Coulomb blockade in strontium titanate thin films

We report on the study of the low temperature electronic transport in strontium titanate thin films having a thickness of 25–30 nm. I-V characteristics measured below 4.2 K show unique structures which are evidence for the occurrence of a Coulomb blockade. Simulations of the measured characteristics suggest that this behavior is closely related to the formation of nanoscopic metallic islands within an insulating matrix which arrange in a network connected via tunneling currents.