Surface and Interface Magnetism Studied by Spin Polarized Light and Electrons

1.自旋极化电子枪的研制用Ar离子束溅射清洗了p型GaAs单晶体，然后在10℃~10℃的超高真空中进行了退火处理。在其上沉积了少量的Cs。随后的O2暴露实现了稳定的负电子亲和势(NEA)光电阴极。光激发是由半导体激光器完成的。NEA阴极的寿命(1/e)在Cs蒸发后约2小时，O_2曝光停止在20微秒。2.用金薄膜制作了扩散散射型电子自旋分析器。散射束的不对称性将由4个独立的Ceratrons来检测。作为自旋分析器前的能量分析器，我们使用了Jost类型的分析器。3：磁性薄膜样品：我们现在在生长在Si(111)衬底上的银薄膜上生长Fe单晶。利用圆偏振同步辐射测量光电子发射强度和角分布的磁圆二向色性正在光子工厂进行。测量了Mn2Sb和MnAlGe的3d、3s态的交换分裂。利用逆光电子能谱对其3d态进行了测量。利用磁圆二色谱对上述化合物中的Mn2p核态进行了测量，给出了不同位置的不同贡献。

1: Development of a spin polarized electron gun A p-type GaAs single crystal was cleaned by Ar ion beam sputtering and then annealed in ultra-high vacuum of 10^<-10> Torr. Small amount of Cs was deposited onto it. Subsequent O_2 exposure realized a stable NEA(negative electron affinity) photo-cathode. The photoexcitation was done by a semiconductor laser. Life time(1/e) of the NEA cathode was about two hours after the Cs evaporation and the O_2 exposure was stopped at 20muA.2: An electron spin analyzer of the diffuse scattering type by use of a Au thin film is manufactured. The asymmetry of the scattered beam is going to be detected by 4 independent Ceratrons. As an energy analyzer in front of the spin analyzer, we use a Jost type analyzer.3: Magnetic thin film sample: We are now growing single crystal of Fe on Ag thin film grown onto Si(111) substrate. Magnetic circular dichroism measurement of the photoemission intensity and angular distribution by use of circularly polarized synchrotron radiation is under way at photon Factory.4. Measurement of the exchange splitting of the 3d, 3s states were done on Mn_2Sb and MnAlGe. Inverse photoemission was fully employed for the measurement of the 3d state.. Magnetic circular dichroism measurement of Mn 2p core states in the above Mn compounds was successfully done providing the different contributions of nonequivalent Mn sites.