Large second-order Josephson effect in planar superconductor-semiconductor junctions
P. Zhang, A. Zarassi, L. Jarjat, V. Van de Sande, M. Pendharkar, J. S. Lee, C. P. Dempsey, A. P. McFadden, S. D. Harrington, J. T. Dong, H. Wu, A. -H. Chen, M. Hocevar, C. J. Palmstrøm, S. M. Frolov
SciPost Phys. 16, 030 (2024) · published 25 January 2024
- doi: 10.21468/SciPostPhys.16.1.030
- Submissions/Reports
Abstract
We investigate the current-phase relations of Al/InAs-quantum well planar Josephson junctions fabricated using nanowire shadowing technique. Based on several experiments, we conclude that the junctions exhibit an unusually large second-order Josephson harmonic, the $\sin(2\varphi)$ term. First, superconducting quantum interference devices (dc-SQUIDs) show half-periodic oscillations, tunable by gate voltages as well as magnetic flux. Second, Josephson junction devices exhibit kinks near half-flux quantum in supercurrent diffraction patterns. Third, half-integer Shapiro steps are present in the junctions. Similar phenomena are observed in Sn/InAs quantum well devices. We perform data fitting to a numerical model with a two-component current phase relation. Analysis including a loop inductance suggests that the sign of the second harmonic term is negative. The microscopic origins of the observed effect remain to be understood. We consider alternative explanations which can account for some but not all of the evidence.
Cited by 5
Authors / Affiliations: mappings to Contributors and Organizations
See all Organizations.- 1 Po Zhang,
- 1 Azarin Zarassi,
- 2 Lucas Jarjat,
- 3 Vince Van de Sande,
- 4 Mihir Pendharkar,
- 4 J. S. Lee,
- 4 Connor P. Dempsey,
- 4 Anthony McFadden,
- 4 Sean David Harrington,
- 4 Jason T. Dong,
- 1 H. Wu,
- 5 A. -H. Chen,
- 5 Moïra Hocevar,
- 4 C. J. Palmstrøm,
- 1 Sergey M. Frolov
- 1 University of Pittsburgh
- 2 École Normale Supérieure [ENS]
- 3 Technische Universiteit Eindhoven / Eindhoven University of Technology [TU/e]
- 4 University of California, Santa Barbara [UCSB]
- 5 Université Grenoble Alpes / Grenoble Alpes University [UGA]
- Agence Nationale de la Recherche [ANR]
- Army Research Office (ARO) (through Organization: United States Army Research Laboratory [ARL])
- National Science Foundation [NSF]
- Office of Naval Research [ONR]