Imaging of electron spin density in coupled semiconductor nanostructures at^3 He temperatures

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One of the great advantages of semiconductor nanostructures is that the electronic states as well as spin states can be designed artificially. This enables us to prepare electronic states in semiconductor nanostructures which manifest novel physical properties. The purpose of this research is to detect novel correlated electronic sates in externally controllable semiconductor nanostructures. We have developed spatially resolved circularly-polarized spectroscopic system at low temperatures and at high magnetic fields. We have successfully developed a low temperature-high magnetic field-near field-scanning optical microscope operated at 70 mK. We have studied imaging of two dimensional electron system and quantum point contacts in high magnetic fields. We have obtained images of broad and narrow strips presumably reflect the diffusion of the optically created electrons in the bulk and the edge states in two dimensional electron system. We have determined of the electron and hole effective masses in perpendicular magnetic fields in the range between 1.5<r_s<6 by magneto-photoluminescence measurements. We find that the obtained effective masses increase with decrease in electron density. The oscillations of the photoluminescence peak energies are observed in quantum tubes depending on the magnetic flux through the tube. These oscillations in energies are shown to be due to the AB effect of a charged exciton in a quantum tube. Our research contributes to realize external control of novel correlated electronic sates in semiconductor nanostructures.