CUED Publications database

On-Chip Andreev Devices: hard Superconducting Gap and Quantum Transport in Ballistic Nb-In0.75Ga0.25As quantum well-Nb Josephson junctions

Delfanazari, K and Puddy, R and Ma, P and Yi, T and Cao, M and Gul, Y and Farrer, I and Ritchie, D and Joyce, H and Kelly, M and Smith, C On-Chip Andreev Devices: hard Superconducting Gap and Quantum Transport in Ballistic Nb-In0.75Ga0.25As quantum well-Nb Josephson junctions. Advanced Materials. (Unpublished)

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Abstract

A superconducting hard gap in hybrid superconductor–semiconductor devices has been found to be necessary to access topological superconductivity that hosts Majorana modes (non-Abelian excitation). This requires the formation of homogeneous and barrier-free interfaces between the superconductor and semiconductor. Here, a new platform is reported for topological superconductivity based on hybrid Nb–In0.75Ga0.25As-quantum-well–Nb that results in hard superconducting gap detection in symmetric, planar, and ballistic Josephson junctions. It is shown that with careful etching, sputtered Nb films can make high-quality and transparent contacts to the In0.75Ga0.25As quantum well, and the differential resistance and critical current measurements of these devices are discussed as a function of temperature and magnetic field. It is demonstrated that proximity-induced superconductivity in the In0.75Ga0.25As-quantum-well 2D electron gas results in the detection of a hard gap in four out of seven junctions on a chip with critical current values of up to 0.2 µA and transmission probabilities of >0.96. The results, together with the large g-factor and Rashba spin–orbit coupling in In0.75Ga0.25As quantum wells, which indeed can be tuned by the indium composition, suggest that the Nb–In0.75Ga0.25As–Nb system can be an excellent candidate to achieve topological phase and to realize hybrid topological superconducting devices.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 23 Aug 2017 20:06
Last Modified: 14 Nov 2017 02:20
DOI: