New Method Of Preparing Giant Magneto-Impedance Film Material And Its Design Of Detection System

Giant magneto-impedance effect is a physical effect that the transformation of alternating current impedance of material is obvious according to the change of external magnetic field. The magnetic sensors using giant magneto-impedance effect has broad prospects In engineering control field. Thin film sensors are advantageous on mass-production and integration of semiconductor circuits, so it is highly valuable to study the GMI effect in soft magnetic film materials. This paper mainly presents the work of two. The first is to introduce a new method of preparing giant magneto-impedance thin film. The second is to describe the design of a new detection system for GMI. Both are based on practical and economical factors. Most reducing cost is the main purpose.At present, the methods of preparing monolayer and multilayer films with GMI effect are mainly by magnetron sputtering. There is no text present the effective way by vacuum evaporation. Because of the high price of the magnetron sputtering coating system, it is hard to popularize. Comparatively, the coating system of vacuum evaporation is very cheap. So the preparation of giant magneto-impedance materials by vacuum evaporation can reduce the productive cost largely. This text presents a practical and feasible method of preparing FeSiB film with GMI effect and overcomes several disadvantages of preparing this kind of films, such as the difficult of controlling the composition ratio, weak film adherence, the poor densification and uniformity, and so on. By solving the problem of no-stable film, the monolayer Film with giant magneto-impedance effect was prepared in glass substrate by vacuum evaporation. Via to transfer the direction of drive current and external magnetic field, four modes of measuring giant magneto-impedance effect were obtained. By comparing, it is found that only if the direction of external magnetic field and uniaxial magnetic anisotropy is apeak, there is the obvious appearance of GMI effect. By comparing the GMI effect of magnetic isotropic and magnetic anisotropy, it is proved that anisotropy is very important in GMI effect and that the feasibility of producing anisotropy by imposing invariable magnetic field in experiment. So the feasibility of preparing the material which have giant magneto-impedance effect by vacuum evaporation was proved.At the same time, considering the price of magnetic impedance measuring instrument produced by Agilent from the United States is very high, we re-design, improve and produce a stable and reliable measurement system for GMI. It based on computer and signal generator, ran stably and reliably, and achieved real-time display! The system can trace out the GMI ratio directly. This paper focuses on the testing process of improvement, principles, parameters selection, process of operation and the analysis of reliability. Testing results show that the system is stable and reliable, real-time display, and affordable. It has basically met the requirements for various materials of giant magneto-impedance. Particularly it is suitable for student's experiment.