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Study of helium three Fermi fluids with controlled interaction and dimensionality

相互作用和维数受控的氦三费米流体研究

基本信息

批准号：
14340104
负责人：
WADA Nobuo
金额：
$ 9.47万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Helium 3 and 4 are typical Fermi and Bose quantum fluids, respectively. In addition to these bulk fluids in three-dimension (3D) and helium films on flat solid surfaces studied so far, we have been studying these quantum fluids confined into nanometer-scale pores that have regular structures from zero to three dimensions. The correlations in these helium fluids can be widely controlled by the density (the amount adsorbed).In the present research, we have established a method to know experimentally how helium atoms form uniform layers on the nanopore walls whose pore diameters are only a few times of the helium atom diameter. In the 1D nano-tunnels of FSM-16,we made helium quantum fluid film tubes on solid helium layers. The 4He Bose fluid tubes show a 1D phonon heat capacities at sufficiently low temperatures where the motion in the crosssection of the tube is in the ground state. We obtained the pore size dependence of the gap energy Δ between the ground state and the first excited state. When a dilute 3He fluid film tubes were formed in the 1D 2.8nm pores preplated by the solid 4He layers, the 3He nanotubes show crossover from the 2D Boltzmann gas at higher temperatures than the gap energy to a 1D degenerate Fermi state at sufficiently low temperatures than Δ/10, below about 30mK.For the 4He fluid films in 3D nanopores of HMM-2 with 2.7nm pore diameter, an obvious evidence of the 3D superfluid transition is suggested by a peak of the heat capacity close to the superfluid onset of the 4He films in contrast to the 2D superfluid transition.In relations to the quantum nuclear magnetic states of the solid 3He, organic antiferromagnets and frustrated magnets have been studied. An S=1 Kagome antiferromagnet with a non-magnetic quantum ground state at zero field was found to have a 1/2 plateau of the magnetization curve.

氦3和氦4分别是典型的费米量子流体和玻色量子流体。除了目前研究的这些三维（3D）散装流体和平坦固体表面上的氦膜外，我们还研究了这些被限制在纳米级孔隙中的量子流体，这些孔隙具有从零到三维的规则结构。这些氦流体中的相关性可以广泛地由密度（吸附量）控制。在本研究中，我们建立了一种实验方法来了解氦原子是如何在孔径仅为氦原子直径几倍的纳米孔壁上形成均匀层的。在FSM-16的一维纳米隧道中，我们在固体氦层上制作了氦量子流体薄膜管。4He玻色流体管在足够低的温度下显示出一维声子热容，其中管的横截面运动处于基态。我们得到了基态和第一激发态之间的间隙能量Δ与孔径的关系。当在固体4He层预涂的一维2.8nm孔隙中形成稀3He流体膜管时，3He纳米管在高于间隙能的温度下从二维玻尔兹曼气体过渡到一维简并费米态，温度低于Δ/10，低于约30mK。对于孔径为2.7nm的HMM-2的三维纳米孔中的4He流体膜，与二维超流转变相比，热容峰值更接近于4He膜的超流起点，这表明了三维超流转变的明显证据。研究了有机反铁磁体和受挫磁体与固体3He的量子核磁态的关系。在零场处具有非磁性量子基态的S=1 Kagome反铁磁体具有磁化曲线的1/2平台。