Research On Thin-Film Hysteresis Loop Measurement System Based On Extraordinary Hall Effect

With the increasingly wider application of the magnetic thin-films, people pay much more attention on the magnetic characterization of the thin-films. The thickness of the thin-films becoming much thinner in many applications ,which make the measurement of the magnetic property parameters of the thin-fims more and more difficult.According to the disadvantages of the traditional test methods,the paper firstly reasearched a method based on extraordinary hall effect.Then a hardware designing scheme focused on the requirements of the experiments was proposed,including using a data acquisition circuit based on PCI bus to acquire and transmitt the data of magnetic field,and some high precision devices to acquire the data of the extraordinary hall voltage,then transmit it through GPIB interface . Then a software developing scheme was proposed,including choose LabView as the development platform to execute the real-time filtering,curve moving and parameters computing. Finally, the experiment results showed that the system could sample, display and process data in high efficiency.In the thesis, the test deviation of the system was analyzed in details from hardware and software aspects,the reason which influence the accuracy was found and a solution was proposed. The results of experiments demonstrated that many factors such as the angle of putting the sample, and the measurement location will effect the accuracy in the test. Through analysis, the method to improve the accuracy of the system is proposed.Theory analysis and the experiment results all showed that,compared to the traditional technology,the test method based on extraordinary hall effect had a huge advantage when testing the hysteresis loop of a very thin film.