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Studies of the flux flow resistivity in YBa₂Cu₃O₆ 95 by microwave techniques Morgan, David Craig
Abstract
Measurements of the microwave surface resistance at 5.4, 27 and 35 GHz on a high quality single crystal of YBa₂Cu₃O₆.₉₅ in magnetic fields up to 8T (applied parallel to the c-axis) and at temperatures from 20K to ]00K are presented. The Coffey-Clem expression for the surface impedance of a superconductor in the mixed state is used to fit the data in terms of a pinning frequency and a free flux flow resistivity (thermal hopping of vortices is not included since it is not important for YBa₂Cu₃O₆.₉₅ at microwave frequencies). A temperature dependent pinning frequency is found that varies from ~20 GHz at 20K to effectively zero by 80K. The flux flow resistivity is strongly temperature dependent and consistent, down to at least 50K, with the Bardeen-Stephen expression pff/pn (T) = H/Hc₂(T) if an extrapolation of the linear normal state resistivity from above Tc is used for pn (T). This suggests that the traditional picture of a vortex core as a cylinder of normal material may be valid in these materials. In contrast, the normal fluid quasiparticle scattering rate, as determined by zero field microwave measurements on the same single crystals¹, drops precipitously below Tc and, thus, is probably not the relevant scattering rate for the charge carriers in the vortex core.
Item Metadata
Title |
Studies of the flux flow resistivity in YBa₂Cu₃O₆ 95 by microwave techniques
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1993
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Description |
Measurements of the microwave surface resistance at 5.4, 27 and 35 GHz on a high
quality single crystal of YBa₂Cu₃O₆.₉₅ in magnetic fields up to 8T (applied parallel to
the c-axis) and at temperatures from 20K to ]00K are presented. The Coffey-Clem
expression for the surface impedance of a superconductor in the mixed state is used to fit
the data in terms of a pinning frequency and a free flux flow resistivity (thermal hopping
of vortices is not included since it is not important for YBa₂Cu₃O₆.₉₅ at microwave
frequencies). A temperature dependent pinning frequency is found that varies from ~20
GHz at 20K to effectively zero by 80K. The flux flow resistivity is strongly temperature
dependent and consistent, down to at least 50K, with the Bardeen-Stephen expression
pff/pn (T) = H/Hc₂(T) if an extrapolation of the linear normal state resistivity from
above Tc is used for pn (T). This suggests that the traditional picture of a vortex core as
a cylinder of normal material may be valid in these materials. In contrast, the normal
fluid quasiparticle scattering rate, as determined by zero field microwave measurements
on the same single crystals¹, drops precipitously below Tc and, thus, is probably not the
relevant scattering rate for the charge carriers in the vortex core.
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Extent |
2269955 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-04-09
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0085663
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.