Study of helium three Fermi fluids with controlled interaction and dimensionality

氦3和氦4分别是典型的费米和玻色量子流体。除了到目前为止研究的三维（3D）和平坦固体表面上的氦膜中的这些体流体之外，我们一直在研究这些量子流体，这些量子流体被限制在纳米级的孔隙中，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通过密度（吸附量）广泛地控制。在本研究中，我们建立了一种实验方法来了解氦原子如何在孔径仅为氦原子直径几倍的纳米孔壁上形成均匀的层。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膜管。的4 He玻色流体管显示在足够低的温度下，在管的横截面中的运动是在基态的一维声子的热容量。我们得到了基态和第一激发态之间的差距能Δ与孔径的关系。当在预先镀有固体4 He层的一维2.8nm孔中形成稀释的3 He流体膜管时，3 He纳米管在高于差距能的温度下从二维Boltzmann气体过渡到低于Δ/10的温度下的一维简并费米态，低于30 mK。与2D超流转变相反，4 He薄膜在超流起始点附近出现热容峰值，这是3D超流转变的明显证据.结合固体3 He的量子核磁态，研究了有机反铁磁体和阻挫磁体.在零场下具有非磁性量子基态的S=1的Kagome反铁磁体的磁化曲线有1/2平台。

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.