A missing step is a key step

Journal Article · Mon Sep 17 00:00:00 EDT 2018 · Nature Materials

DOI:https://doi.org/10.1038/s41563-018-0179-1· OSTI ID:1502455

Zhang, Fan ^[1]; Pan, Wei ^[2]

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1. Univ. of Texas, Dallas, Richardson, TX (United States). Dept. of Physics
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

In a uniform superconductor, electrons form Cooper pairs that pick up the same quantum mechanical phase for their bosonic wavefunctions. This spontaneously breaks the gauge symmetry of electromagnetism. In 1962 Josephson predicted, and it was subsequently observed, that Cooper pairs can quantum mechanically tunnel between two weakly coupled superconductors that have a phase difference Φ. The resulting supercurrent is a 2π periodic function of the phase difference Φ across the junction. This is the celebrated Josephson effect. More recently, a fractional Josephson effect related to the presence of Majorana bound states — Majoranas — has been predicted for topological superconductors. This fractional Josephson effect has a characteristic 4π periodic current–phase relation. Now, writing in Nature Materials, Chuan Li and colleagues report experiments that utilize nanoscale phase-sensitive junction technology to induce superconductivity in a fine-tuned Dirac semimetal Bi_0.97Sb_0.03 and discover a significant contribution of 4π periodic supercurrent in Nb–Bi_0.97Sb_0.03–Nb Josephson junctions under radiofrequency irradiation.

• Research Organization: Sandia National Lab. (SNL-CA), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000; NA0003525
• OSTI ID: 1502455
• Report Number(s): SAND-2018-10061J; 667848
• Journal Information: Nature Materials, Vol. 17, Issue 10; ISSN 1476-1122
• Publisher: Springer Nature - Nature Publishing Group
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY