Abstract
Characteristics of SN(F/N)nIN(F/N)mS Josephson junctions with n, m=1 to 3 are reported. Here, S is a superconductor (Nb), F is a magnetic material (nickel), nitrogen is a nonmagnetic metal (aluminum), and I is an insulator (Al/AlOx). The devices with n=m=1 and n=1, m=2 display critical current versus magnetic field [Ic(H)] dependences that imply the appearance of fractional magnetic vortices in the junction, corresponding to a half of the flux quantum. Stochastic switching between the two half-vortex polarities with emission of an integer vortex was observed. In the devices with n=m=3, a typical Ic(H) dependence consists of a background current with a large modulation period, and a Fraunhofer-like pattern with a small modulation period on top of the background current. The Fraunhofer-like pattern may be completely or partially inverted; in these states, there is a component of the Josephson current flowing against the bias current, indicating the presence of the π phase in the junction. The experiments give evidence that switching between the zero and π states can, potentially, be magnetically controlled.
Original language | English (US) |
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Article number | 024503 |
Journal | Physical Review B |
Volume | 108 |
Issue number | 2 |
DOIs | |
State | Published - Jul 1 2023 |
Funding
This research received support from the NSF (Grant No. DMR 1905742) and from the NSF DISCoVER Expedition award (Grant No. CCF-2124453). The author acknowledges the use of facilities of the Materials Research Center at Northwestern University, supervised by J. B. Ketterson and supported by the NSF. The author thanks M. A. Belogolovskii for fruitful discussions.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics