skip to main content


This content will become publicly available on October 6, 2018

Title: Critical current oscillations of elliptical Josephson junctions with single-domain ferromagnetic layers

We report that josephson junctions containing ferromagnetic layers are of considerable interest for the development of practical cryogenic memory and superconducting qubits. Such junctions exhibit a ground-state phase shift of π for certain ranges of ferromagnetic layer thicknesses. We present studies of Nb based micron-scale elliptically shaped Josephson junctions containing ferromagnetic barriers of Ni 81Fe 19 or Ni 65Fe 15Co 20. By applying an external magnetic field, the critical current of the junctions is found to follow characteristic Fraunhofer patterns and display sharp switching behavior suggestive of single-domain magnets. The high quality of the Fraunhofer patterns enables us to extract the maximum value of the critical current even when the peak is shifted significantly outside the range of the data due to the magnetic moment of the ferromagnetic layer. The maximum value of the critical current oscillates as a function of the ferromagnetic barrier thickness, indicating transitions in the phase difference across the junction between values of zero and π. Lastly, we compare the data to previous work and to models of the 0-π transitions based on existing theories.
ORCiD logo [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [3]
  1. Michigan State Univ., East Lansing, MI (United States). Department of Physics and Astronomy
  2. Northrop Grumman Systems Corporation, Baltimore, MD (United States)
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0021-8979; 659178; TRN: US1800255
Grant/Contract Number:
AC04-94AL85000; NA0003525
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 122; Journal Issue: 13; Journal ID: ISSN 0021-8979
American Institute of Physics (AIP)
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, null
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); IARPA
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Superconductivity; Josephson Junction; Ferromagnetism; Cryogenic Memory; Proximity Effect
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1398292