Microstructure and electrical transport properties of nanoscale [(CO₄₀Fe₄₀B₂₀)₃₄(SiO₂)₆₆/(In₂O₃)/C]₄₆ multilayers

Abstract

We investigated the role of microstructure and In2O3/C interlayer thickness on the electrical transport properties of [(Co40Fe40B20)34(SiO2)66/(In2O3)/C]46 multilayers prepared using ion-beam sputtering. These multilayers were characterized using an X-ray diffraction, X-ray reflectivity, impedance spectroscopy, and magnetoresistive measurements. The X-ray diffraction data showed that regardless of the layer thickness, all components of the multilayers are X-ray amorphous. Fitting X-ray reflectivity data, multilayer periodicities are extracted and layers thicknesses, densities and roughnesses are determined. Impedance spectroscopy has shown a resistive-capacitive coupling between electrically conductive ferromagnetic CoFeB clusters which corresponds to the model of a prepercolation composite. For the thinnest multilayer with nonmagnetic In2O3/C interlayer thickness of about 1.6 nm, we managed to achieve a magnetoresistance of about 0.8% at room temperature and 3.2% at cryogenic temperature.