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。除了这些三维(3D)中的体相流体和平面固体表面上的氦薄膜，我们一直在研究这些限制在纳米尺度气孔中的量子流体，这些气孔具有从零到三维的规则结构。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的几倍的纳米孔壁上形成均匀的层的。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表现出一维声子热容量，此时管内横截面的运动处于基态。我们得到了基态和第一激发态之间的能隙能量Δ与孔径的关系。当在预镀有固体4He层的一维2.8 nm孔中形成稀薄的3He流体薄膜管时，3He纳米管在高于带隙能量的温度下从二维玻尔兹曼气体跨越到一维简并费米态，温度低于Δ/10，低于30mK。对于孔径为2.7 nm的HMM-2三维纳米孔中的4He流体薄膜，与二维超流体相变相反，在接近4He薄膜超流体起始位置的热容峰值表明了3D超流体相变的明显证据。与固体3He的量子核磁状态相比，对有机反铁磁体和受阻磁体进行了研究。零场非磁量子基态的Kagome反铁磁体S=1的磁化曲线具有1/2的平台。

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.