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Doctoral Thesis
DOI
https://doi.org/10.11606/T.54.1983.tde-19082014-093410
Document
Author
Full name
Hiroshi Tejima
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1983
Supervisor
Committee
Souza, Milton Ferreira de (President)
Levy, Moisés
Missell, Frank Patrick
Oliveira, Luiz Nunes de
Ortiz, Wilson Aires
Title in Portuguese
Atenuação de ondas acústicas superficiais em filmes finos granulares supercondutores de Pb
Keywords in Portuguese
Atenuação
Filme fino
Ondas acústicas
Abstract in Portuguese
Este trabalho tem por objetivo a investigação de atenuação de ondas acústicas superficiais (OAS) em filmes finos granulares supercondutores de PbO e Pb depositados por sputtering reativo em substratos piezoelétricos de LiNbO3 e quartzo (ST). As medidas de atenuação de OAS em função da temperatura foram efetuadas para diferentes potências de radiofreqüência, e em freqüência variando de 550 MHz a aproximadamente 700 MHz. A atenuação de OAS medida em filme granular de chumbo (550Å), dotada de alta resistividade de filme (de 1000 Ω/〈) se manifesta piezoeletricamente induzida e proporcional à resistividade do filme. No estado supercondutor esta medida de atenuação excede esta simples relação. Esta atenuação excedente é atribuída à resistência local produzida pela presença de dipolos de vórtice-antivórtice
Title in English
Surface acoustic waves attenuation in granular superconducting Pb thin films
Keywords in English
Acoustic wave
Attenuation
Thin film
Abstract in English
The subject of this work is the investigation of surface acoustic waves (SAW) on superconducting Pb and PbO granular thin films deposited by sputtering on piezoelectric substrate (LiNbO3 and quartz ST). The SAW attenuation was measured as a function of the temperature (1,3K to 20K) for different r.f. Power, in frequencies from 550 MHz to 700 MHz. The SAW attenuation, measured on granular lead film (550 Å) with high sheet resistivity (1000 Ω/〈) appears to be piezoelectrically induced and should be proportional to the sheet resistivity. In the superconducting state the measured attenuation exceeds this simple relation. This excess attenuation is ascribed to the local resistance produced by the presence of vortex-antivortex dipoles
 
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HiroshiTejimaD.pdf (3.37 Mbytes)
Publishing Date
2014-08-21
 
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