PHOTOEMISSION OF SPIN-POLARIZED ELECTRONS FROM GAAS
PHOTOEMISSION OF SPIN-POLARIZED ELECTRONS FROM GAAS
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DOI：
10.1103/physrevb.13.5484
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发表时间：
1976-01-01
影响因子：
3.7
通讯作者：
MEIER, F
中科院分区：
文献类型：
--
作者：
PIERCE, DT;MEIER, F
用Mott散射测量了能量为1.5<ω<3.6eV的圆偏振光照射下（110）GaAs光致发射电子的自旋极化。GaAs表面用铯和氧处理以获得负电子亲和势（NEA）。自旋极化P（π ω）的光谱在阈值处呈现出由在Γ处的跃迁引起的峰（P= 40%）以及分别在3.0和3.2 eV处的正峰（P= 8%）和负峰（P=-8%），其由在L（Λ）处的跃迁引起。异常的行为，包括在阈值的去极化和峰值极化在1.7 eV的增加和移位到54%，是由于一个小的正电子亲和势（PEA）的一些样品的特性。光电子发射角的限制直接导致了P的过高。计算结果表明，对于NEA GaAs中的Γ跃迁发射，P不能增加50%以上。我们的详细解释的光谱表明自旋极化光电子能谱可以用来研究电子结构的自旋相关方面。本文讨论了NEA GaAs作为自旋极化电子源的优异性能，并与其它源进行了比较。
The spin polarization of electrons photoemitted from (110) GaAs by irradiating with circlarly polarized light of energy 1.5< ℏ ω< 3.6 eV was measured by Mott scattering. The GaAs surface was treated with cesium and oxygen to obtain a negative electron affinity (NEA). The spectrum of spin polarization P (ℏ ω) exhibits a peak (P= 40%) at threshold arising from transitions at Γ and positive (P= 8%) and negative (P=− 8%) peaks at 3.0 and 3.2 eV, respectively, arising from transitions at L (Λ). Anomalous behavior, consisting of a depolarization at threshold and an increase and shift in the peak polarization to 54% at 1.7 eV, is attributed to a small positive electron affinity (PEA) characteristic of some samples. Restriction of the photoelectron emission angle by the PEA leads directly to the anomalously high P. Results of calculations show that P cannot be increased above 50% for emission arising from transitions at Γ in NEA GaAs. Our detailed interpretation of the spectra indicates how spin-polarized photoemission can be used to study the spin-dependent aspects of electronic structure. The outstanding qualities of NEA GaAs as a source of spin-polarized electrons are discussed and compared with other sources.