Presidential Young Investigator Award

强磁场作用下二维电子系统(2DES)的基态性质吸引了大量的实验和理论研究。由于系统地努力优化设计和生长工艺，他们已经开发出包含非常高迁移率、低密度和极低无序的2DES的GaAs/GaAlAs异质结。实现高质量的低电子浓度的2DES是特别有意义的，因为它们提供了在可用磁场中实现和研究在新的极端磁量子极限区域中2DES的基本性质的手段。磁输运、激活输运和非线性输运测量将被用来研究2DES的集体态--分数量子霍尔态和量子Wigner晶体--以及磁场在2DES中的局域化。射频磁谱将被用来研究这些状态下的集体激发。电子束微区照相术将被用来用同样最先进的材料制造纳米结构。上述实验技术将被用来研究受限几何(直至200A)中2DES的集体态。

The nature of the ground state of a two-dimensional electron system (2DES) subjected to an intense magnetic field has attracted a great deal of research, both experimental and theoretical. As a result of a systematic effort to optimize the design and the growth process they have developed GaAs/GaAlAs heterostructures containing very high-mobility, low-density 2DES with extremely low disorder. The realization of high-quality 2DES with low electron concentration is of particular interest because they provide the means to achieve and study fundamental properties of 2DES in a new regime of extreme magnetic quantum limit in available magnetic fields. Magnetotransport, activated transport and nonlinear transport measurements will be used to investigate collective states of 2DES - the Fractional Quantum Hall states and quantum Wigner crystal - and the magnetic-field- induced localization in 2DES. Radiofrequency magnetospectroscopy will be used to study collective excitations in these states. Electron beam microlitography will be used to fabricate nanostructures from the same state-of-the-art materials. The above described experimental techniques will be employed to study collective states of 2DES in restricted geometry (down to 200A).