Complete Analysis Of Evolution Of Induced Electromotive Force In A Vibrating Sample Magnetometer

Vibrating sample magnetometer(VSM)is the most widely used equipment for magnetic measurement.The investigation on VSM is mainly focused on the sensitivity and steadiness of signals,which are both related to a key parameter,i.e.the sensitivity function.In ever performed analyses on VSM,the sensitivity function is usually replaced with its zero-order term,and consequently,the induced Induction electromotive force(IEF)is a single sine or cosine wave.However,the sensitivity actually varies periodically with the vibrating of sample.In this dissertation,the IEF is strictly analyzed by considering the variation of IEF.It is found that the wave forms of IEF generally exhibit distortion compared to an ideal sine or cosine wave,demonstrating that the IEF signal contains a series of higher harmonics as well as a fundamental frequency signals,and it is the amplitude of fundamental frequency component that is extracted by the lock-in amplifier equipped in VSM system.Then,we calculate the amplitude of fundamental frequency component and compare it with the result achieved by using the conventionally adopted sensitivity function.It isfound that the conventionally adopted sensitivity function is unable to give correct saddle range,and even fails to give true sensitivity when there occurs transversal displacement of sample.In conclusion,the analyzing the sensitivity and signals steadiness of VSM should base on the amplitude of fundamental frequency component of IEF.