Temperature dependence of a twofold magnetic behaviour of a nanoscopic metal/silicon hybrid system – a comparison between Ni/Si and Co/Si

Abstract

The investigated hybrid nanocomposite consists of a porous silicon template with electrochemically embedded Ni or Co nanostructures and offers magnetic characteristics which can be tailored by the electrochemical process parameters during fabrication. A twofold magnetic behaviour can be observed, a first one due to the spinmagnetism at magnetic fields below the saturation magnetization of the deposited metals and a second non‐saturating term at higher fields (> 1 T up to 7 T) above the saturation magnetization. In case of Ni deposited within the pores this non‐saturating term shows a paramagnetic characteristic and follows exactly the Curie‐Weiss law, whereas for Co/porous silicon samples the temperature dependent magnetization shows some deviations from the Curie Weiss law. In this high field region a difference in the temperature dependence between Ni and Co is observed whereas the non‐saturating term does not depend on the geometry of the embedded nanostructures in contrast to the ferromagnetic behaviour at lower magnetic fields. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)