Local and Nonlocal Fraunhofer-like Pattern from an Edge-Stepped Topological Surface Josephson Current Distribution
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- 作者：Jae Hyeong Lee ; Gil-Ho Lee ; Joonbum Park ; Janghee Lee ; Seung-Geol Nam ; Yun-Sok Shin ; Jun Sung Kim ; Hu-Jong Lee
- 刊名：Nano Letters
- 出版年：2014
- 出版时间：September 10, 2014
- 年：2014
- 卷：14
- 期：9
- 页码：5029-5034
- 全文大小：317K
- ISSN：1530-6992
文摘
We report a surface-dominant Josephson effect in superconductor鈥搕opological insulator鈥搒uperconductor (S鈥揟I鈥揝) devices, where a Bi1.5Sb0.5Te1.7Se1.3 (BSTS) crystal flake was adopted as an intervening TI between Al superconducting electrodes. We observed a Fraunhofer-type critical current modulation in a perpendicular magnetic field in an Al鈥揟I鈥揂l junction for both local and nonlocal current biasing. Fraunhofer-type modulation of the differential resistance was also observed in a neighboring Au鈥揟I鈥揂u normal junction when it was nonlocally biased by the Al鈥揟I鈥揂l junction. In all cases, the Fraunhofer-like signal was highly robust to the magnetic field up to the critical field of the Al electrodes, corresponding to the edge-stepped nonuniform supercurrent density arising from the top and rough side surfaces of the BSTS flake, which strongly suggests that the Josephson coupling in a TI is established through the surface conducting channels that are topologically protected.