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On‐Chip Andreev Devices: Hard Superconducting Gap and Quantum Transport in Ballistic Nb–In 0.75 Ga 0.25 As‐Quantum‐Well–Nb Josephson Junctions
Author(s) -
Delfanazari Kaveh,
Puddy Reuben K.,
Ma Pengcheng,
Yi Teng,
Cao Moda,
Gul Yilmaz,
Farrer Ian,
Ritchie David A.,
Joyce Hannah J.,
Kelly Michael J.,
Smith Charles G.
Publication year - 2017
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201701836
Subject(s) - superconductivity , condensed matter physics , josephson effect , materials science , andreev reflection , topology (electrical circuits) , supercurrent , physics , mathematics , combinatorics
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–In 0.75 Ga 0.25 As‐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 In 0.75 Ga 0.25 As 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 In 0.75 Ga 0.25 As‐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 In 0.75 Ga 0.25 As quantum wells, which indeed can be tuned by the indium composition, suggest that the Nb–In 0.75 Ga 0.25 As–Nb system can be an excellent candidate to achieve topological phase and to realize hybrid topological superconducting devices.