Influence of substrate effects in magnetic and transport properties of magnesium ferrite thin films

Abstract

In order to study substrate influence in Mg ferrite properties, thin films weresimultaneously grown by DC magnetron sputtering on different substrates (MgO(100) and SrTiO3 (100)). In both cases samples show high values of saturationmagnetization and Curie temperatures above room temperature. While in thecase of the sample grown on MgO the hysteresis loops indicate the existenceof more than one ferrimagnetic component and lower value of remanence tosaturation ratio, the deposited one on SrTiO3 is mono-component and has arectangular-shape magnetic loop at all temperatures below 300 K. The differenceis attributed to different microstructures due to the misfit strain caused by thedifferent lattice constants between substrates and ferrite. The electric transport and photoconductivity properties have been investigated on both samples. Thin film growth on STO presents an increase around 40% of the photoconductance in the near UV range. The photocurrent shows two clear onsets that coincide with the indirect and direct band gaps of STO indicating the important role of this substrate in the generation of photo carriers.