Eur. Phys. J. B 76, 353-357 (2010)
https://doi.org/10.1140/epjb/e2010-00183-5

Superconducting transition in Pb/Co nanocomposites: effect of Co volume fraction and external magnetic field

¹ Centro Brasileiro de Pesquisas Físicas, Rua Dr.Xavier Sigaud 150, Rio de Janeiro, 22290-180 RJ, Brazil
² Instituto de Física, Universidade Federal do Rio de Janeiro, Cx. P. 68528, 21941-972 Rio de Janeiro, Brazil

Corresponding author: ^a xing@cbpf.br

Received: 5 April 2010
Revised: 7 May 2010
Published online: 17 June 2010

Abstract

Pb films embedded with homogeneously distributed cobalt (Co) nanoparticles (mean size 4.5 nm) have been prepared. Previous transport investigations have suggested that Co particles induce spontaneous vortices below the superconducting transition temperature (T_c) in zero external magnetic field. In this paper we study in detail the influence of the Co volume fraction and an external magnetic field on the superconducting transition in such composites. The large difference in T_c-reduction between the as-prepared and annealed samples can be attributed to the different superconducting coherence lengths and the resulting different diameters of the spontaneous vortices in these samples.