Magnetism and tunnelling magnetoresistance of Fe nanoparticles embedded in ZnSe epilayers
Résumé
We report on the magnetic and magnetotransport properties of Fe clustered particles embedded in a ZnSe matrix. The samples are prepared by molecular beam epitaxy and consist of discontinuous Fe planes of unconnected particles covered by a 4.5 nm-thick epilayer of ZnSe, repeated in 20 cycles. Scanning tunnelling microscopy and transmission electron microscopy revealed well isolated and regularly dispersed Fe nanoparticles. This particle assembly displays a dominant superparamagnetic response with weak inter-particle magnetic interactions. The magnetotransport experiments performed in the current-in-plane geometry showed a negative magnetoresistance of 2% at low temperature, which is described by localized states through a ZnSe semiconducting barrier.