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Non-Fraunhofer interference pattern in inhomogeneous ferromagnetic Josephson junctions.
Mohammad Alidoust1, Granville Sewell, Jacob Linder
1Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway. phymalidoust@gmail.com
Physical Review Letters
|March 10, 2012
Summary
Ferromagnetic Josephson junctions exhibit non-Fraunhofer responses when subjected to magnetic fields. Inhomogeneities in energy scales like Thouless energy and exchange fields disrupt standard patterns, revealing complex "0-π" state interactions.
Area of Science:
- Condensed Matter Physics
- Quantum Superconductivity
Background:
- Ferromagnetic Josephson junctions are crucial for superconducting spintronics.
- The critical supercurrent response to magnetic fields typically follows a Fraunhofer pattern.
Purpose of the Study:
- To establish conditions for non-Fraunhofer critical supercurrent responses in ferromagnetic Josephson junctions.
- To theoretically explain observed deviations from the standard Fraunhofer pattern.
Main Methods:
- Utilizing the quasiclassical Keldysh-Usadel method.
- Investigating the influence of energy scale inhomogeneities (Thouless energy, exchange field, temperature gradient) on the supercurrent.
Main Results:
- Demonstrated that inhomogeneities in energy scales drastically alter the Fraunhofer pattern.
- The exotic non-Fraunhofer response arises from the interplay of multiple "0-π" states.
- Proximity vortices are linked to the appearance of this non-Fraunhofer behavior.
Conclusions:
- Theoretical framework established for non-Fraunhofer responses in ferromagnetic Josephson junctions.
- Inhomogeneities are key to understanding deviations from standard magnetic field dependencies.
- The findings provide insights into the complex physics of "0-π" states and proximity effects.
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