Issue Europhys. Lett. Volume 75, Number 6, September 2006 Page(s) 943 - 949 Section Condensed matter: electronic structure, electrical, magnetic, and optical properties DOI 10.1209/epl/i2006-10218-2 Published online 23 August 2006

Europhys. Lett., 75 (6), pp. 943-949 (2006)
DOI: 10.1209/epl/i2006-10218-2

Enhancing superconductivity: Magnetic impurities and their quenching by magnetic fields

T.-C. Wei, D. Pekker, A. Rogachev, A. Bezryadin and P. M. Goldbart

Department of Physics, University of Illinois at Urbana-Champaign 1110 West Green Street, Urbana, IL 61801-3080, USA

received 10 April 2006; accepted in final form 1 August 2006
published online 23 August 2006

Abstract
Magnetic fields and magnetic impurities are each known to suppress superconductivity. However, as the field quenches (i.e. polarizes) the impurities, rich consequences, including field-enhanced superconductivity, can emerge when both effects are present. In superconducting wires and thin films this field-spin interplay is investigated via the Eilenberger-Usadel scheme. Non-monotonic dependence of the critical current on the field (and therefore field-enhanced superconductivity) is found to be possible, even in parameter regimes for which the superconducting critical temperature decreases monotonically with increasing field. The present work complements that of Kharitonov and Feigel'man (JETP Lett., 82 (2005) 421), which predicts regimes of non-monotonic behavior of the critical temperature.

PACS
74.25.Sv - Critical currents.
74.62.-c - Transition temperature variations.
74.78.-w - Superconducting films and low-dimensional structures.

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