Fundamental Research on Spin-filter with highly Spin-polarized Electrons

自旋极化电子源的发展：开发了GaAs-GaAsP应变超晶格的自旋极化电子源。获得了0.7%的量子效率和77%的极化率或0.3%的量子效率和80%的极化率。另一种类型的源已被研究与大块砷化镓。在这种情况下，电子是通过吸收圆偏振激光的两个光子来激发的。根据选择规则，只有特定自旋方向的电子被选择性激发。通过对发光极化的测量，估计受激电子的初始极化率为86%。旋转过滤器的研制。采用溅射法在GaAs衬底上沉积了一层GdTbFe铁磁薄膜。薄膜与薄膜垂直磁化。然后，自旋极化电子在衬底中被激发并注入薄膜中。在被激发的电子自旋方向与磁化方向平行或反平行的情况下，测量了光电流。观察了铁磁薄膜滤光片的滤光效果。

Development of spin-polarized electron sources : Spin-polarized electron sources with GaAs-GaAsP strained supperlattice were developed. The quantum efficiency of 0.7% as well as the polarizability of 77% has been obtained or the quantum efficiency of 0.3% as well as the polarizability of 80% has been obtained. Another type of sources has been studies with bulk GaAs. In this case electrons are excited by absorbing two photons of circularly polarized laser. By the selection rule, only electrons of a definite spin direction are selectively excited. The initial polarization of the excited electrons was estimated to be 86% from the measurement of the polarization of the luminescence.Development of spin-filter. A ferromagnetic thin film of GdTbFe was deposited on a GaAs substrate by the sputtering method. The film was magnetized perpendicularly to the film. Then, the spin-polarized electrons were excited in the substrate and injected in the film. The photo currents were measured under the condition that the spin direction of the electrons excited is parallel or anti-parallel to the direction of the magnetization. The clear effect of the filter by the ferromagnetic film was observed.