Electrical properties of ferromagnetic-insulator nanocomposites

Abstract

Abstract. Analysis of experimental studying of electrical properties of ferromagnetic-insulator nanocomposites is presented in the paper.The investigation of composite materials consisting from ferromagnetic metal nanoparticles distributed in insulating matrix is one of promising directions in the condensed state physics. Scientific interest to the such nanocomposites is caused by the fact that presence of the nanometer-sized ferromagnetic particles leads to appearance of unique electrical, galvanomagnetic, optical and magneto-optical properties. As examples of the most significant properties, we can note the tunneling magnetoresistance reaching 12-13% at room temperature [1], the giant Hall effect, which is four orders of magnitude greater than the given effect in pure metals [2], the magnetorefractive effect which is two orders of magnitude greater than the traditional magneto-optical effects [3] and others phenomenon [4][5]. This paper is devoted to analysis of our experimental data on the study of electrical properties of ferromagnetic-insulator nanocomposites and the mechanisms of charge carrier transfer established in them.Various charge carrier transfer mechanisms are realized in ferromagnetic-insulator nanocomposites in pre-percolation region [6]. The first frequently found mechanism is the hopping conductivity via localized states near the Fermi level with a variable hopping range (Mott's model).In this case the electrical conductivity can be described by the following equation [7]