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Giant Mesoscopic Fluctuations and Long-Range Superconducting Correlations in Superconductor-Ferromagnet Structures
A S Mel'nikov1,2, A I Buzdin3
1Institute for Physics of Microstructures, Russian Academy of Sciences, 603950 Nizhny Novgorod, GSP-105, Russia.
Physical Review Letters
|August 27, 2016
Summary
Giant mesoscopic fluctuations in dirty hybrid structures impact the Usadel equations
Area of Science:
- Condensed matter physics
- Superconductivity
- Mesoscopic physics
Background:
- The Usadel equations are widely used to describe superconductivity in disordered systems.
- Proximity effects in hybrid structures are crucial for understanding superconducting properties.
- Mesoscopic scales introduce unique phenomena due to quantum interference.
Purpose of the Study:
- To investigate the impact of fluctuating superconducting correlations on the Usadel formalism at mesoscopic scales.
- To explain anomalously slow decay of superconducting correlations in superconductor-ferromagnet structures.
- To elucidate the origin of long-range proximity phenomena in mesoscopic samples.
Main Methods:
- Theoretical analysis of fluctuating superconducting correlations.
- Examination of interference effects in Cooper pair wave functions.
- Modeling of superconductor-ferromagnet-superconductor junctions and hybrid structures.
Main Results:
- Fluctuating superconducting correlations affect the validity of Usadel equations at mesoscopic scales.
- Giant mesoscopic fluctuations, driven by exchange fields, cause slow decay of superconducting correlations in ferromagnets.
- Sample-to-sample fluctuations in Josephson current and local density of states explain long-range proximity effects.
Conclusions:
- The study highlights limitations of the Usadel formalism at mesoscopic scales due to fluctuations.
- Mesoscopic fluctuations provide a mechanism for long-range proximity phenomena in superconductor-ferromagnet systems.
- Understanding these fluctuations is key for designing and interpreting experiments in mesoscopic superconductivity.
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