Studies of Two Dimensional Quantum Fluids and Solids with Low Temperature LEED and STM

用比热测量方法研究了氦-3（3 He）和氦-4（4 He）在石墨表面吸附的第一层和第二层的低温量子相图。理论上意想不到的二维3 He的多体凝聚被发现。此外，在3 He和4 He的第二层中存在相称的固相被证实，这也是第一性原理计算所没有预料到的。我们首次成功地用低温STM对氪在石墨表面的单层吸附进行了实空间成像，证实了氪的吸附位置是石墨蜂窝晶格的中空位置。成功完成了在稀释制冷机温度下工作的LEED仪器开发的可行性研究。

Low temperature quantum phase diagrams of the first and second layers of helium-3 (3He) and helium-4 (4He) adsorbed on graphite were studied by specific heat measurements. Theoretically unexpected many-body condensation of two-dimensional 3He was discovered. In addition, the existence of a commensurate solid phase in the second layer of both 3He and 4He was confirmed, which had also been unexpected from the first-principles calculations. This phase is presumably a low-density quantum solid with zero-point defectons.We succeeded in the first real-space imaging of monolayer of Krypton adsorbed on graphite with low temperature STM and confirmed the adsorption site of Kr to be the hollow site of graphite honeycomb lattice. A feasibility study of development of a LEED instrument which works at dilution refrigerator temperatures was successfully finished.