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INVITATION OF THE SUPERCONDUCTING PROXIMITY EFFECT (SPE)
AND MAGNETIC DEAD LAYERS (MDL)
IN THIN FILM DOUBLE LAYERS
by
Go Tateishi
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(PHYSICS)
May 2009
Copyright 2009 Go Tateishi
Object Description
| Title | Investigation of the superconducting proximity effect (SPE) and magnetc dead layers (MDL) in thin film double layers |
| Author | Tateishi, Go |
| Author email | gotateishi@hotmail.com; go_tateishi@yahoo.co.jp |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Physics |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2008-11-20 |
| Date submitted | 2009 |
| Restricted until | Unrestricted |
| Date published | 2009-03-12 |
| Advisor (committee chair) | Bergmann, Gerd |
| Advisor (committee member) |
Nakano, Aiichiro Lu, Jia Grace Haas, Stephan Thompson, Richard S. |
| Abstract | When a thin superconducting film (S film) is condensed onto a thin normal conducting film (N film), the first layers of the S film loose their superconductivity. This phenomenon is generally called the "superconducting proximity effect(SPE)". As an investigation of SPE we focus on the transition temperature of extremely thin NS double layers in the thin regime. Normal metal is condensed on top of insulating Sb, then Pb is deposited on it in small steps. The transition temperature is plotted in an inverse Tc-reduction 1/dTc=1/(Ts-Tc) versus Pb thickness graph. To compare our experimental results with the theoretical prediction, a numerical calculation of the SN double layer is performed by our group using the linear gap equation. As a result, there are large discrepancies between the experimental and theoretical results generally. The results of the NS double layers can be divided into three groups in terms of their discrepancies between experiment and theory.(1) Non-coupling(Tc=0K):N= Mg, Ag, Cu, Au. There are large deviations between experiment and theory by a factor to the order of 2.5. (2) Weak coupling (Tc is low(<2.5K):N=Cd, Zn, Al. Deviation is present, but only by a factor of 1.5. (3) Intermediate coupling(Tc is around half of Pb's(4.5K)): N=In, Sn. The experimental results agree with the theory.; Next, we examine the detection of the magnetic dead layer (MDL) of Ni thin films in terms of the anomalous Hall effect (AHE) with several non-magnetic metal substrates. In our results, when Ni film is contact with a polyvalent metal substrate film, the sandwich film has around 2 to 3.5 at.lay. of magnetic dead layers. However we have not observed the magnetic dead Ni layers with the alkali and noble metal substrate film.; Finally, we revisit the Pb/Ni system to measure the magnetic scattering of Ni with the method of Weak Localization (WL) to compare with the dephasing rate due to the Tc-reduction. In this series, we use only very thin Pb films between 1.3 and 5 at.lay. deposited on top of the Ag substrate with about 37 at.lay. thickness, because we make the Ag substrate suppress the superconductivity of the extremely thin Pb film with the SPE and avoid the Azlamazov-Larkin fluctuations. After comparison, it becomes clear that the dephasing rate from the Tc-reduction method is much larger than that measured by the weak localization (the factor is around 120). We consider not only "pair breaking" but also "pair weakening", and conclude that the reduction of the superconducting transition temperature is not due to dephasing by magnetic scattering but due to the resonance scattering of Cooper pairs by non-magnetic d-states. |
| Keyword | magnetic dead layers; superconducting proximity effect; thin metal film |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m2019 |
| Rights | Tateishi, Go |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Tateishi-2569 |
| Archival file | uscthesesreloadpub_Volume51/etd-Tateishi-2569.pdf |
Description
| Title | Page 1 |
| Full text | INVITATION OF THE SUPERCONDUCTING PROXIMITY EFFECT (SPE) AND MAGNETIC DEAD LAYERS (MDL) IN THIN FILM DOUBLE LAYERS by Go Tateishi A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (PHYSICS) May 2009 Copyright 2009 Go Tateishi |
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