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Title: High-precision measurement of magnetic penetration depth in superconducting films

We report that the magnetic penetration depth (λ) in thin superconducting films is usually measured by the mutual inductance technique. The accuracy of this method has been limited by uncertainties in the geometry of the solenoids and in the film position and thickness, by parasitic coupling between the coils, etc. Here, we present several improvements in the apparatus and the method. To ensure the precise thickness of the superconducting layer, we engineer the films at atomic level using atomic-layer-by-layer molecular beam epitaxy. In this way, we also eliminate secondary-phase precipitates, grain boundaries, and pinholes that are common with other deposition methods and that artificially increase the field transmission and thus the apparent λ. For better reproducibility, the thermal stability of our closed-cycle cryocooler used to control the temperature of the mutual inductance measurement has been significantly improved by inserting a custom-built thermal conductivity damper. Next, to minimize the uncertainties in the geometry, we fused a pair of small yet precisely wound coils into a single sapphire block machined to a high precision. Lastly, the sample is spring-loaded to exactly the same position with respect to the solenoids. Altogether, we can measure the absolute value of λ with the accuracy bettermore » than ±1%.« less
Authors:
 [1] ;  [1] ; ORCiD logo [2] ;  [3]
  1. Yale Univ., New Haven, CT (United States). Dept. of Applied Physics
  2. Zensoft, Inc., Madison, WI (United States)
  3. Yale Univ., New Haven, CT (United States). Dept. of Applied Physics; Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-113152-2016-JA
Journal ID: ISSN 0034-6748; RSINAK; R&D Project: KC0203020; MA209MACA
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1336172
Alternate Identifier(s):
OSTI ID: 1331829

He, X., Gozar, A., Sundling, R., and Božović, I.. High-precision measurement of magnetic penetration depth in superconducting films. United States: N. p., Web. doi:10.1063/1.4967004.
He, X., Gozar, A., Sundling, R., & Božović, I.. High-precision measurement of magnetic penetration depth in superconducting films. United States. doi:10.1063/1.4967004.
He, X., Gozar, A., Sundling, R., and Božović, I.. 2016. "High-precision measurement of magnetic penetration depth in superconducting films". United States. doi:10.1063/1.4967004. https://www.osti.gov/servlets/purl/1336172.
@article{osti_1336172,
title = {High-precision measurement of magnetic penetration depth in superconducting films},
author = {He, X. and Gozar, A. and Sundling, R. and Božović, I.},
abstractNote = {We report that the magnetic penetration depth (λ) in thin superconducting films is usually measured by the mutual inductance technique. The accuracy of this method has been limited by uncertainties in the geometry of the solenoids and in the film position and thickness, by parasitic coupling between the coils, etc. Here, we present several improvements in the apparatus and the method. To ensure the precise thickness of the superconducting layer, we engineer the films at atomic level using atomic-layer-by-layer molecular beam epitaxy. In this way, we also eliminate secondary-phase precipitates, grain boundaries, and pinholes that are common with other deposition methods and that artificially increase the field transmission and thus the apparent λ. For better reproducibility, the thermal stability of our closed-cycle cryocooler used to control the temperature of the mutual inductance measurement has been significantly improved by inserting a custom-built thermal conductivity damper. Next, to minimize the uncertainties in the geometry, we fused a pair of small yet precisely wound coils into a single sapphire block machined to a high precision. Lastly, the sample is spring-loaded to exactly the same position with respect to the solenoids. Altogether, we can measure the absolute value of λ with the accuracy better than ±1%.},
doi = {10.1063/1.4967004},
journal = {Review of Scientific Instruments},
number = 11,
volume = 87,
place = {United States},
year = {2016},
month = {11}
}

Works referenced in this record:

High-temperature interface superconductivity between metallic and insulating copper oxides
journal, October 2008
  • Gozar, A.; Logvenov, G.; Kourkoutis, L. Fitting
  • Nature, Vol. 455, Issue 7214, p. 782-785
  • DOI: 10.1038/nature07293