Europhys. Lett.
Volume 66, Number 1, April 2004
Page(s) 111 - 117
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 March 2004
Europhys. Lett., 66 (1) , pp. 111-117 (2004)
DOI: 10.1209/epl/i2004-10003-3

Spin screening of magnetic moments in superconductors

F. S. Bergeret1, 2, A. F. Volkov1, 3 and K. B. Efetov1, 4

1  Theoretische Physik III, Ruhr-Universität Bochum - D-44780 Bochum, Germany
2  Laboratorio de Física de Sistemas Pequeños y Nanotecnología, CSIC Serrano 144, E-28006 Madrid, Spain
3  Institute of Radioengineering and Electronics of the Russian Academy of Sciences 103907 Moscow, Russia
4  L. D. Landau Institute for Theoretical Physics - 117940 Moscow, Russia

(Received 6 January 2004; accepted 2 February 2004)

We consider ferromagnetic particles embedded into a superconductor and study the screening of their magnetic moments by the spins of the Cooper pairs in the superconductor. It is shown that a magnetic moment opposite to the one of the ferromagnetic particle is induced in the superconductor. In the case of a small itinerant ferromagnet grain and low temperatures, the full screening of the magnetic moment takes place, i.e. the absolute value of the total magnetic moment induced in the superconductor is equal to the one of the ferromagnetic particle. In type-II superconductors the proposed screening by spins of the conduction electrons can be much stronger than the conventional screening by Meissner currents.

74.45.+c - Proximity effects; Andreev effect; SN and SNS junctions.
74.25.Ha - Magnetic properties.

© EDP Sciences 2004