Single-Electron Tunneling Effects at the Surfaces of Oxide Superconductor Films
We have studied charging effects arising from tunnel junctions with ultrasmall capacitances using a cryogenic STM. Our samples are evaporated thin films of high temperature superconductors whose surface morphology is often rich in microstructures. All our measurements are made at 4.2K and above, and after approaching the surface, I-V characteristics are obtained. The I-V curves often displayed characteristics arising from the Coulomb blockade of ultrasmall tunneling junctions. In one measurement, we have observed clearly what appeared to be microwave induced current steps possibly due to the SET oscillations. Some of the results are compared with numerical calculations.
KeywordsHigh Temperature Superconductor Tunnel Junction Current Step Highly Orient Pyrolytic Graphite Coulomb Blockade
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- I. Takeuchi, J.S. Tsai, S. Ishizaka, T. Yoshitake, and S. Satoh, to appear in the proceedings of Materials and Mechanisms of Superconductivity, High Temperature Superconductors IIIGoogle Scholar