Size effect in Ni_x(MgO)_(100-x) nanocomposites

摘要

The possibility of obtaining a nanostructured composite in the Ni-Mg-O system by ionbeam sputtering has been investigated. The structural, magnetic and magnetoresistive properties of obtained samples have been investigated in a wide concentration range. The presence of the nanostructure in the obtained samples with Ni nanogranules (2-3 nm) has been confirmed by transmission electron microscopy. There is no observation of any magnetic or magnetoresistive properties at room temperature in the Ni_x(MgO)_(100-x) composites. These properties were observed at 77 K. The obtained data mean that Curie temperature of the Ni nanogranules is lower then 298 K. This is due to small size of nickel granules and low value of exchange interaction energy in nickel.