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| Identifier |
000381509 |
| Title |
Spin-orbit interaction in hybrid Josephson junctions |
| Alternative Title |
Αλληλεπίδραση σπιν-στροφορικής σε επαφές Josephson |
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Author
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Αλεξανδράκης, Ματθαίος
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Thesis advisor
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Φλυτζάνης, Νικόλαος
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Reviewer
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Ζώτος, Ξενοφών
Εφραιμίδης, Νικόλαος
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| Abstract |
In this Master's Thesis we study the Rashba spin-orbit coupling effect
(RSOC) on the supercurrent and zero-phase current of a short, ballistic
Josephson junction, in the clean limit. The junction consists of two s-wave
superconductors (S) and three layers in between, a 2-dimensional electron gas
(2DEG) between two ferromagnets (F) (S/IF /F/2DEG/F/IF /S). In addition, we have two thin insulator interfaces (IF,) between the superconductors
and the ferromagnets, capable of both normal scattering and spin-flip due to
inhomogeneous magnetization.
We study this junction by observing how the absolute value of the critical
supercurrent, the zero-phase current and the current-phase relation (CPR)
change when we introduce a 2DEG layer with spin-orbit coupling.
The effects produced by magnetization and spin-orbit coupling are compared. The 2-dimensional electron gas is placed on the xy plane, and that
means it produces an electric field, parallel to the z axis, with the induced
magnetic field on the plane where the carriers move. As we increase spin-
orbit coupling we observe that the magnetization geometry has a strong effect
on physical properties. In the half-metallic limit, where due to spin (down) cut-
off, singlet correlations diminish, while triplet correlations are induced, which
enable long range supercurrent.
Spin-orbit interaction changes the 0- π transitions observed due to the
magnetization. Also, it breaks the degeneracy for the supercurrent of geometries with equal supercurrent. Oscillations in the critical supercurrent
are attributed to exchange fields but also to resonances in the 2DEG inter-
mediate layer, which scale in width like λ-1. In the half-metallic limit we
see strong triplet correlations, which are especially noticed outside the cut-off points in kp. Triplet correlations exist even for smaller exchange fields along with singlet correlations. For this, the magnetization geometry is crucial.
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| Language |
English |
| Subject |
Current-phase relation (CPR) |
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Half-metallic limit. |
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Rashba spin-orbit coupling effect |
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Singlet correlations |
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Triplet correlations |
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Zero-phase current |
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Ημι-μεταλλικό όριο |
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Συ- σχετισμοί παράλληλου σπίν (triplet) |
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Συσχετισμοί αντιπαράλληλου σπίν (singlet) |
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Σχέση ρεύματος-φάσης (CPR) |
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Υπερρεύμα μηδενικής φάσης |
| Issue date |
2013-11-15 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Physics--Post-graduate theses
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Type of Work--Post-graduate theses
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| Views |
588 |
Spin-orbit interaction in hybrid Josephson junctions
