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Anomalous Supercurrent Modulation in Josephson Junctions With Ni-Based Barriers
Burm Baek1, Michael L Schneider1, Matthew R Pufall1
1National Institute of Standards and Technology, Boulder, CO 80305 USA.
IEEE Transactions on Applied Superconductivity : a Publication of the IEEE Superconductivity Committee
|March 27, 2025
Summary
We studied magnetic Josephson junctions with nickel barriers, observing oscillatory critical current. Anomalous features suggest unique microscopic transport effects in these magnetic devices.
Area of Science:
- Condensed Matter Physics
- Superconductivity
- Spintronics
Background:
- Josephson junctions are fundamental superconducting devices.
- Magnetic Josephson junctions offer unique properties due to the exchange field.
- Understanding transport in magnetic Josephson junctions is crucial for spintronic applications.
Purpose of the Study:
- To investigate supercurrent transport characteristics in Ni-barrier Josephson junctions.
- To analyze the influence of multilayer barrier structures on junction properties.
- To explore anomalous features in magnetic Josephson junctions.
Main Methods:
- Fabrication of Josephson junctions with varying nickel barrier multilayer structures.
- Magneto-electrical measurements for detailed characterization.
- Analysis of critical current oscillations and current-phase relationships.
Main Results:
- Observed oscillatory critical current as a function of Ni thickness, largely matching clean-limit theory.
- Identified anomalous features: phase shift due to nonmagnetic spacer, near-zero magnetic dead layer, and distorted current-phase relationship near the 0-π transition.
- These results highlight the complex interplay of exchange fields and superconducting spin modulation.
Conclusions:
- The study reveals unique microscopic transport phenomena in magnetic Josephson junctions.
- Findings provide insights into the role of the exchange field in superconducting spin modulation.
- A path towards a comprehensive understanding of realistic magnetic Josephson junctions is discussed.
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