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Theory of anomalous proximity effects in phase-coherent structures

Claughton, N R and Hui, V C and Lambert, Colin (1995) Theory of anomalous proximity effects in phase-coherent structures. Physical Review B, 51 (17). pp. 11635-11646. ISSN 0163-1829

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Abstract

We present theoretical results for the change δG in the electrical conductance G of a mesoscopic sample due to the switching on of superconductivity. Due to competition between normal and Andreev scattering, the sign of δG depends in detail on the impurity configuration within a device. In contrast with universal conductance fluctuations, we demonstrate that δG can scale with the system size and therefore, as well as being negative, can have a magnitude much greater than 2e2/h. For clean systems, this anomalous behavior arises from low-angle quasiparticle scattering at normal-superconducting interfaces. For dirty systems it arises from the presence of normal-state conductance resonances. We also examine the magnetic-field dependence of δG and show that fields on the scale of a flux quantum through a sample can change the sign of δG and suppress its magnitude. For a superconducting order parameter of magnitude Δ0, we present results for the Δ susceptibility χΔ=limΔ0→0∂G(Δ0)/∂Δ02. For clean systems, where the normal-state conductance is quantized in units of 2e2/h, we predict that χΔ diverges at normal-state conductance steps. For dirty systems, it is shown that χΔ is sensitive to the local environment of single impurity atoms.

Item Type: Article
Journal or Publication Title: Physical Review B
Subjects: Q Science > QC Physics
Departments: Faculty of Science and Technology > Physics
ID Code: 58145
Deposited By: ep_importer_pure
Deposited On: 25 Oct 2012 14:51
Refereed?: Yes
Published?: Published
Last Modified: 10 Apr 2014 00:08
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/58145

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