Effect of GaAs substrate on the magnetic properties of Ni film

In this paper, temperature and field dependent magnetization processes of N i films are studied. Polycrystalline Ni films are deposited on n-type GaAs (001) and Si (001) substrates by both the usual thermal evaporation and the UHV deposition in a MBE system. The roughness and the inherent oxide layer of the substrate are taken into consideration while preparing the Ni film on GaAs substrate. For a comparative study, similar Ni films deposited on g lass substrate and a bulk Ni sample are investigated as well. At low temper ature, considerably large applied fields are required to gradually saturate the Ni/GaAs films.. starting from the end of the hysteresis. As an associa te phenomenon, a large reduction of the remanent moment is observed. Coerci ve field as high as 71 mT is observed for this Ni film on GaAs substrate at 4.2 K. These anomalous magnetic behaviors are considered to be the effects of GaAs substrate, as they do not appear in Ni films deposited on Si subst rate. glass substrate. and in the bulk Ni sample. A local anti ferro magnet ic interaction among the Ni spins at the interface of Ni and GaAs has been speculated. This interaction becomes stronger as the temperature goes below the room temperature. (C) 2001 Elsevier Science B.V. All rights reserved.