Development of Giant Magnetoresistance Material Based on Cobalt Ferrite

This paper describes an experimental study on development of giant magnetoresistance material based on cobalt ferrite (CoFe₂O₄). We have successfully developed a new giant magnetoresistance material based on CoFe₂O₄ i.e; sandwich (CoFe₂O₄/CuO/CoFe₂O₄), spin valve (FeMn/CoFe₂O₄/CuO/CoFe₂O₄), and organic giant magnetoresistance (CoFe₂O₄/Alq₃/CoFe₂O₄) using dc-opposed target magnetron sputtering method. Crystalline structure and morphology of thin films were characterized by X-ray diffraction and scanning electron microscope. The electrical properties were characterized using a four-point probe and magnetic properties were characterized using a vibrating sample magnetometer. In sandwich structure, the giant magnetoresistance ratio maximum are found at room temperature in CoFe₂O₄/CuO/CoFe₂O₄ thin film is 70% when CoFe₂O₄ and CuO layer thickness are 62.5 nm and 14.4 nm, respectively. The maximum of giant magnetoresistance ratio of the spin valve structure obtained is 32.5% at FeMn layer thickness of 45 nm. Meanwhile, in organic giant magnetoresistance the maximum value of the giant magnetoresistance ratio are approximately 35.5% at room temperature.