Spin Polarization Dependent Far Infrared Absorption in Ga1-xMnxAs
Spin Polarization Dependent Far Infrared Absorption in Ga1-xMnxAs
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Ga1-xMnxAs 中自旋偏振相关的远红外吸收
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
H. Ohno
中科院分区：
文献类型：
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作者：
Y. Nagai;T. Kunimoto;K. Nagasaka;H. Nojiri;M. Motokawa;F. Matsukura;T. Dietl;H. Ohno
测量了铁磁Ga_（1-x）Mn_xAs（x=0.034和x=0.050）在10 ~ 12000 cm ~（-1）范围内的红外和远红外透射光谱。在1600 cm-1附近观察到一个宽峰，该能量接近GaAs中Mn杂质的深受主能级。一个有限的无特征的吸收，这个峰和带隙之间的传播，由于价带间跃迁也观察到。同时，在所研究的最低频率下观察到非零吸收，其指向与金属DC电导率相关的移动的空穴的吸收。在这个范围内的频率依赖性，这显着不同于德鲁德模型，表现出强烈的影响，静电和磁无序的光学电导率。特别是，Mn自旋和空穴之间的强耦合的存在解释了铁磁有序温度以下的远红外吸收的显著增加。
Infrared and far infrared transmission spectra have been measured for the ferromagnetic Ga1-xMnxAs (x=0.034 and x=0.050) between 10 and 12000 cm-1. A broad peak is observed around 1600 cm-1, and this energy is close to the deep acceptor level of Mn impurity in GaAs. A finite featureless absorption, spreading between this peak and the band gap, due to inter valence band transitions is also observed. At the same time, a non-zero absorption is observed in the lowest frequency studied, which points to the absorption by mobile holes related to the metallic DC conductivity. The frequency dependence in this range, which differs markedly from the Drude model, demonstrates a strong influence of electrostatic and magnetic disorder on the optical conductivity. In particular, the existence of a strong coupling between the Mn spins and the holes explains the considerable increase of the far infrared absorption below the ferromagnetic ordering temperature.