Electron correlation and magnetic field effect in two dimensional electron systems in semiconductors

点击翻译按钮获取中文摘要

We have studied electronic and magnetic states in strongly correlated two-dimensional systems formed in Si-MOSFETs, Si/SiGe heterostructures, and p-GaAs/AlGaAs heterostructures.1)We have developed a rotatory sample stage used in a dilution refrigerator.2)We observed a metallic behavior even for the completely spin polarized state in a Si/SiGe sample. We proposed a phase diagram for the condition of the metallic phase on the plane of disorder vs internal degree of freedom.3)We found that the ground state in the insulating phase of a Si-MOSFET is not ferromagnetic.4)Magnetotransport in the insulating phase has been measured for n-Si,n-GaAs and p-GaAs samples. The results indicate that giant resistivity oscillations can be observed for strongly correlated systems.5)We observed a giant positive magnetoresistance in the insulating phase ofa 2D hole system.6)We have performed cyclotron resonance and electron spin resonance measurements for a Si/SiGe sample.