Study of magnetism by total reflection angle X ray spectroscopy with spin polarized electron beam

我们的目的不仅是要确定元素，而且要通过仔细测量由自旋极化入射电子引起的铁磁样品中磁性原子的特征X射线强度来获得表面原子磁矩的信息。我们自行设计并研制了一套GaAs极化电子源超高真空系统。我们做了以下三个实验。1)铁<alpha><beta>磁金属Fe、Co、Ni在自旋极化电子激发下的K_1和K_2特征X射线的密集测量平行和反平行的自旋极化的铁磁样品的磁化强度的情况下，没有观察到的K线强度的差异。2)铁磁Co-Pd合金样品中Pd的L线的仔细测量。4d* 2 p跃迁的特征X射线被识别，但当入射电子的自旋极化反转时，几乎没有观察到明显的差异。Co-Pd合金中Pd的4d电子的极化可能不足以被检测到。3)Fe的L线出现电位谱。软X射线是用750 A铝滤光片后的通道管探测的。观察到L核激发的出现电位峰。该峰强度依赖于入射电子相对于样品磁化的自旋极化。定性分析将在进一步强化实验后进行。

We intended to try not only to specify elements but also to get the information about magnetic moment of the atoms at the surface by careful measurements of the characteristic X ray intensities which arise from magnetic atoms in a ferromagnetic specimen by spin polarized incident electrons. An UHV system with a polarized electron source of GaAs was designed and manufactured by ourselves. The following three experiments have been done. 1) Intensive measurements of K_<alpha>, and K_<beta> characteristic X ray of Fe, Co, and Ni ferromagnetic metal exited by spin polarized electrons. No differences of K line intensities were observed between the cases with parallel and antiparallel spin polarization to the magnetization of the ferromagnetic samples. 2) Careful measurements of L line of Pd in a ferromagnetic Co-Pd alloy sample. The characteristic X ray for 4d*2p transition was identified, but there was hardly observed clear differences when the spin polarization of incident electrons was reversed. The polarization of 4d electrons of Pd in Co-Pd alloy may not be sufficient to be detected. 3) Appearance potential spectroscopy for L line of Fe. Soft X ray was detected by a channeltron behind a 750A Al filter. Appearance potential peak of L core excitation was observed. This peak intensities was dependent on the spin polarization of incident electrons with respect to the sample magnetization. Qualitative analysis will be done after further intensive experiments.