Cross-sectional magnetic domain analysis by three-dimensional magnetic charge distribution measurement in magnetic thin films

点击翻译按钮获取中文摘要

In order to improve the recording density for recent high density magnetic recording media, the observation and control of magnetic domain structure for these films in not only the film plain direction but also the cross-sectional direction of films is strongly needed, because of the reduction of medium noise due to tlie fluctuation of magnetization. In the present study, the method of three-dimensional magnetic charge distribution measurement in magnetic thin films by using magnetic force microscope (MFM) was investigated. The following results are obtained.1) Three-dimensional magnetic chargedistribution measurement is possible in the case that the resolution of MFM is limited by the digitizing resolution of the input signals in MFM. This measurement can be done by subtracting the experimentally obtained MFM signals from the transformed MFM signals with same tip-sample distance to which are transformed from the signals measured at different tip-sample distance by MFM signal transformation method. This method is verified by computer simulation2) For three-dimensional magnetic charge distribution measurement, the MFM tip whose magnetic direction does not change by the stray field of MFM samples at short tip-sample distance is needed. We developed high coercivity MFM tips coated by sputtered L10 ordered CoPt films with Hc = 14kOe.3) For three-dimensional magnetic charge distribution measurement, it is important to know the MFM tip magnetization. Therefore we developed the method of in-situ magnetic hysteresis measurement of MFM tips by detecting the alternating force of MFM tips with applying alternating magnetic field to MFM tips.4) The improvement of MFM resolution is effective for three-dimensional magnetic charge distribution measurement. We developed the high-resolution MFM with 10 nm resolution by increasing the dynamic range of MFM input signals and using Lock-in amplifier to reduce signal noise.