Speaker
Description
Using a hydrogen annealing process, we have successfully fabricated intrinsic Josephson junction (IJJ) tunneling devices in Bi2Sr2CaCu2Oy (Bi-2212) high-temperature superconductor. To flow electrical current along c-axis direction, a Bi-2212 single crystal was annealed in a hydrogen atmosphere at 300-500℃ for 15-60 minutes. By the annealing, an electrical property of the Bi-2212 single crystal between electrodes was deteriorated. Therefore, a current pathway was changed from ab-plane direction to c-axis direction. The annealed Bi-2212 single crystal showed clear voltage jumps in current-voltage characteristics.
To investigate how the intrinsic Josephson junction tunneling device is formed by the new process, we carried out X-ray photoemission spectroscopy. From Cu 2p XPS spectra obtained at Bi-2212 single crystals annealed in hydrogen-nitrogen mixed gas, we found that Cu ions in a new region were reduced. The new region does not show a superconducting property in R-T characteristics because of the high resistivity. Therefore, it is expected that the new region changes a current pathway. The change of a current pathway probably leads to an attainment of IJJ tunneling devices. Our process is expected to have great advantages in its technical simplicity.
| Submitters Country | 日本 |
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