| 报告题目 | Spin properties of holes in GaAs nanostructures. |
| 报告人 | Prof. A.R. Hamilton |
| 报告人单位 | School of Physics, University of New South Wales, Australia |
| 报告时间 | 2014-07-15 |
| 报告地点 | 合肥微尺度物质科学国家实验室九楼会议室 |
| 主办单位 | 合肥微尺度物质科学国家实验室、国际功能材料量子设计中心 |
| 报告介绍 | Abstract：
The electrical current in a semiconductor can be carried by negatively charged electrons or positively charged holes. In undergraduate physics, we are often taught that holes in the valence band are just an absence of an electron. But they aren’t. Valence band holes are spin-3/2 particles, and this gives them very different properties to spin-1/2 electrons, particularly when confined to low dimensions. In this talk I will present some recent results from our group:
1. We have fabricated high quality hole quantum wires that show clean and stable quantized conductance plateaus. In contrast to 1D electron quantum systems, the spin-splitting in these hole wires is highly anisotropic, and depends only on the orientation of the in-plane magnetic field relative to the quantum wire. However the orientation and k-dependence of the spin-splitting cannot be reconciled with existing theories, suggesting that more theoretical work is needed before we understand the physics of spin-3/2 holes, even on `simple' (100) surfaces.
2. We have also studied the coupling between nuclear and hole spins in 2D electron and hole systems. For 2D electrons we are able to detect nuclear magnetic resonance features revealing coupling of electron and nuclear spins in the GaAs crystal. For 2D hole systems however we were unable to detect coupling between hole and nuclear spins over a wide range of hole densities, consistent with a greatly reduced hyperfine interaction.
Our results show that holes are much more complex than equivalent electron systems, and there is much theoretical and experimental work to do before they are understood. |
