一种加偏压减小磁场对样品电流信号影响的方法

A method for reducing the influence of external field on sample current by adding bias voltage

在用样品电流法测量X射线磁性圆二色谱中,外磁场的存在严重降低了样品电流信号。针对合肥NSRL软X射线磁性圆二色实验站内置式可旋转磁铁设计并安装一个紧靠磁极的高压金网,来增强磁场下的样品电流信号。发现不同磁场下随偏压升高,样品电流信号迅速增强并趋于饱和;磁场越强,达到饱和需要的偏压越高;比较相同磁场和偏压下均匀氧化的Al箔和CoFe薄膜正反磁场下的吸收谱,发现加磁场和偏压引入的系统误差仅相当于Co的圆二色值的2.17%;表明用这种方法进行X射线磁性圆二色谱的测量是可行的。

In measuring X-ray magnetic circular dichroism spectra by the sample current mode, signal currents are strongly affected by external fields. Aiming at the design of rotatable electromagnet inside the vacuum chamber, we have designed and installed a piece of gold mesh attached to magnetic poles to increase the sample current signals, and found that sample currents increase rapidly and tend to saturation with increasing bias in different magnetic fields The stronger the external field is applied, the higher bias voltage is required to reach signal saturation. Comparing absorption spectra of an oxidated aluminum foil with a CoFe film in parallel and antiparallel magnetization under the same magnetic field and bias, we have found that the systematic error caused by adding magnetic field and bias is 2.17% of MCD intensity for cobalt, which indicates that the developed technique has some advantages to measure XMCD spectra.