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Effect of inhomogeneous coupling on BCS superconductors

Zou, Yue and Klich, Israel and Refael, Gil (2008) Effect of inhomogeneous coupling on BCS superconductors. Physical Review B, 77 (14). Art. No. 144523. ISSN 1098-0121. doi:10.1103/PhysRevB.77.144523.

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We investigate the influence of inhomogeneity in the pairing coupling constant U(r-vector) on dirty BCS superconductors, focusing on Tc, the order parameter Delta(r-vector), and the energy gap Eg(r-vector). Within mean-field theory, we find that when the length scale of the inhomogeneity is comparable to or larger than the coherence length, the ratio 2Eg/Tc is significantly reduced from that of a homogeneous superconductor, while in the opposite limit, this ratio stays unmodified. In two dimensions, when strong phase fluctuations are included, the Kosterlitz-Thouless temperature TKT is also studied. We find that when the inhomogeneity length scale is much larger than the coherence length, 2Eg/TKT can be larger than the usual BCS value. We use our results to qualitatively explain recent experimental observation of a surprisingly low value of 2Eg/Tc in thin films.

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Additional Information:©2008 The American Physical Society. (Received 18 December 2007; published 25 April 2008) We would like to thank D. Podolsky for several enlightening discussions. The work of I.K. was supported in part by the National Science Foundation under Grant No. PHY05-51164.
Subject Keywords:BCS theory; coherence length; dirty superconductors; Kosterlitz-Thouless transition; superconducting energy gap; superconducting thin films; superconducting transition temperature
Issue or Number:14
Record Number:CaltechAUTHORS:ZOUprb08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10340
Deposited By: Archive Administrator
Deposited On:30 Apr 2008
Last Modified:08 Nov 2021 21:07

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