单个InP/GaInP点中的Overhauser效应
Overhauser effect in individual InP/GaInP dots
摘要：
在磁场B_ext=0- 5 T的宽范围内，利用圆偏振光激发，在单个InP/GaInP点中实现了较大的核自旋极化。我们观察到在Bext=1.5T时高达~40%的核极化，对应于~1.2T的Overhauser场。我们发现核自旋对自旋抽运效率有很强的反馈作用。这种由Overhauser场产生的反馈导致在Bext=0.5-1.5T的低磁场下的核自旋双稳态。我们发现，激子塞曼能量显着增加时，Overhauser场抵消外场。这种反直觉的结果表明，产生的电子和空穴塞曼分裂的总激子塞曼能量的相反的贡献。
英文摘要：
Sizable nuclear spin polarization is pumped in individual InP/GaInP dots in a wide range of external magnetic fields B_ext=0-5T by circularly polarized optical excitation. We observe nuclear polarization of up to ~40% at Bext=1.5T and corresponding to an Overhauser field of ~1.2T. We find a strong feedback of the nuclear spin on the spin pumping efficiency. This feedback, produced by the Overhauser field, leads to nuclear spin bi-stability at low magnetic fields of Bext=0.5-1.5T. We find that the exciton Zeeman energy increases markedly, when the Overhauser field cancels the external field. This counter-intuitive result is shown to arise from the opposite contribution of the electron and hole Zeeman splittings to the total exciton Zeeman energy.
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