Magnetic properties of Ni-doped MgO diluted magnetic insulators

Abstract

Magnesium oxide doped with Ni has been studied in two different forms: one in which the Ni ions are incorporated into the substitutional sites and the other in which Ni is present both in substitutional sites and in the form of metallic Ni precipitates embedded in the MgO matrix. Magnetic properties of these materials have been studied and correlated with the microstructural properties. There is a significant difference in the magnetic properties between the two forms. From these studies the authors envisage that a diluted magnetic insulator will be paramagnetic in the absence of intrinsic defects such as vacancies and interstitials. MgO is a good system to perform the present studies as it can be synthesized as a high quality crystal devoid of defects to a high degree. Moreover, the magnetic properties of the Ni precipitates can be used to compare the results when a diluted magnetic semiconductor material is not fully devoid of nanoclusters/precipitates and secondary phases. © 2007 American Institute of Physics.