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Competing effects of surface phonon softening and quantum size effects on the superconducting properties of nanostructured Pb

Bose, Sangita and Galande, Charudatta and Chockalingam, S P and Banerjee, Rajarshi and Raychaudhuri, Pratap and Ayyub, Pushan (2009) Competing effects of surface phonon softening and quantum size effects on the superconducting properties of nanostructured Pb. Journal of Physics: Condensed Matter, 21 (20). p. 205702.

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Official URL: http://stacks.iop.org/0953-8984/21/i=20/a=205702

Abstract

The superconducting transition temperature ( T C ) in nanostructured Pb decreases from 7.24 to 6.4 K as the particle size is reduced from 65 to 7 nm, below which superconductivity is lost rather abruptly. In contrast, there is a large enhancement in the upper critical field ( H C2 ) in the same size regime. We explore the origin of the unusual robustness of T C over such a large particle size range in nanostructured Pb by measuring the temperature dependence of the superconducting energy gap in planar tunnel junctions of Al / Al 2 O 3 / nano - Pb. We show that below 22 nm, the electron–phonon coupling strength increases monotonically with decreasing particle size, and almost exactly compensates for the quantum size effect, which is expected to suppress T C .

Item Type:Article
ID Code:11354
Deposited By:Prof. Alexey Ivanov
Deposited On:02 Nov 2011 00:13
Last Modified:02 Nov 2011 00:47

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