Of Fe <sub> 3 </ Sub> The O <sub> 4 </ Sub> Thin Film Characterization And Preparation

Fe₃O₄ is a kind of classic half-metallic material. It has the highest spin polarization about 84% measured in room temperature and provides Curie temperature with 858K. At present, the characteristics for single-crystalline Fe₃O₄ films have been researched in detail but polycrystalline Fe₃O₄ film is seldom researched. Under such research background, this article focusses on fabricating and measuring the polycrystalline Fe₃O₄ thin film and a set of magnetoelectronics transit test system is designed according to the laboratory request.In this paper, the emphasis of research is to build a measurement system of magnetoelectronics transit, and we fabricate Fe₃O₄ film by dc magnetron sputtering.The main contents of research are as follows:1.Adopting virtual instrument and single chip technology, automatic measurement of electromagnet's magnetic field and system of magnetoelectronics transit is realized.2.Fabricating uniphase Fe₃O₄ film by dc magnetron sputtering, the influence of sputtering power, annealing temperature is discussed in detail and the optimum fabricating condition is found.3.The influence of Ta buffer introduced to Fe₃O₄ film is investigated in detail.4. Using our measurement system, the magnetoresistance effect of the polycrystalline film is measured.The measurement system of magnetoelectronics transit is proved with high accuracy and good repetition in actual use, which provides a kind of effective and trustworthy measure method for material research. During the course of film fabrication, we find that sputtering power and annealing temperature are the most important factors that influence the structure and quality of Fe₃O₄ film. Researching them ,the optimum condition of fabricating pure Fe₃O₄ is founded. Otherwise, using the Ta buffer layer can effectively reduce the surface roughness. In addition, measured by our measurement system, the polycrystalline the film has similar negative magnetoresistance effect to single-crystalline film, so it is potential to be applied in spintronic devices.