Measurement of MOKE Hysteresis Loop Using Non-uniform Sampling

Abstract

There are two parts in MOKE hysteresis loops, typical for materials with perpendicular magnetic anisotropy. One is due to a steeply falling edge or rising edge accompanied by the sign changes in magneto-optical Kerr effect (MOKE) signal. The other corresponds to a slow change of non-transition segment. A satisfying tradeoff between response to rapid change and noise rejection in non-transition segment of the loop is hardly obtained. The problem may be solved using a method based on non-uniform sampling. Its goals are to reduce distortion of the transitional waveform and noise, to obtain high resolution of transitional waveform and to decrease the number of sampling points. This paper describes the principle of non-uniform sampling and its implementation, and we designed a comparative experiment using a constant sampling frequency and multi-sampling frequency. The result shows that the measurement system with non-uniform sampling can reduce distortion of the MOKE loops, improve the accuracy of the coercivity, and decrease the number of sampling points.