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Observation of Andreev bound states at spin-active interfaces
F Hübler1, M J Wolf, T Scherer
1Institut für Nanotechnologie, Karlsruher Institut für Technologie, Karlsruhe, Germany.
Physical Review Letters
|September 26, 2012
Summary
We observed unique subgap conductance features in superconductor-ferromagnet junctions, revealing insights into spin-dependent phase shifts and the triplet proximity effect.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Phenomena
Background:
- Superconductor-ferromagnet heterostructures are crucial for spintronic devices.
- Understanding interfacial effects is key to controlling emergent quantum phenomena like triplet proximity.
Purpose of the Study:
- To investigate spin-dependent transport phenomena in nanoscale superconductor-ferromagnet tunnel junctions.
- To determine interfacial phase shifts using Andreev bound states.
Main Methods:
- High-resolution differential conductance spectroscopy.
- Fabrication of superconductor-ferromagnet tunnel junctions with ultrathin oxide barriers.
- Application of external magnetic fields to probe Zeeman splitting.
Main Results:
- Observed bias-symmetric subgap conductance features.
- Demonstrated Zeeman energy-dependent shifts of these features.
- Explained features by resonant transport via Andreev bound states.
Conclusions:
- Successfully determined the magnitude and sign of spin-dependent interfacial phase shifts.
- Provided microscopic insight into the triplet proximity effect at spin-active interfaces.
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