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Size-dependent resistivity in a micro-processed YBa2Cu3O7-δ superconducting whisker

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Authors
De La Pierre, Marco
Cagliero, S.
Agostino, A.
Gazzadi, G.
Truccato, M.
Date
2009
Type
Journal Article

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De La Pierre, M. and Cagliero, S. and Agostino, A. and Gazzadi, G. and Truccato, M. 2009. Size-dependent resistivity in a micro-processed YBa2Cu3O7-δ superconducting whisker. Superconductor Science and Technology. 22 (4): Article ID 045011.
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Superconductor Science and Technology
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Department of Applied Chemistry
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This is an author-created, un-copy edited version of an article accepted for publication in De La Pierre, M. and Cagliero, S. and Agostino, A. and Gazzadi, G. and Truccato, M. 2009. Size-dependent resistivity in a micro-processed YBa2Cu3O7-δ superconducting whisker. Superconductor Science and Technology. 22 (4): Article ID 045011. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://doi.org/10.1088/0953-2048/22/4/045011

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Abstract

We report the results of a detailed geometrical and electrical study which has been performed on a YBa2Cu3O7-δ superconducting whisker. This sample has undergone three subsequent steps of micro-machining by means of a focused ion beam (FIB) instrument, in order to progressively decrease its cross-sectional area from ~77 to ~4 µm2, over a length of about 150 µm. A simple analytical model based on the exact shape both of the electrical contacts and of the micro-machined material has been proposed for the voltage drop; besides, an accurate geometrical characterization of all of the sample details has been performed by means of SEM microscopy. This enabled us to extract accurate electrical resistivity curves from the resistance versus temperature characteristics for each of the fabrication steps of the whisker, showing an increase of the sheet resistivity with decreasing cross-sectional area. Among the possible physical reasons for such behaviour, inelastic electron scattering at the sample surfaces has been ruled out because of the very short mean free path of carriers in YBCO. On the other hand, oxygen out-diffusion and Ga ion implantation due to the FIB processing are most likely to be responsible for the observed resistivity trend.