One-Dimensional 4 He and 3 He Quantum Fluids Realized in Nanopores
Nobuo Wada
Department of Physics, Nagoya University, Nagoya 464-8602, Japan
To realize one-dimensional (1D) helium fluids, we have studied 4 He and 3 He adsorbed onto FSM-16 that
has straight 1D nanopores from 18 to 47Å in diameter. Quantum fluids appear on the nanopore walls
covered with solid helium layers. Since the azimuthal motion in the 1D nanopores has discrete energy
levels, there remains only one degree of freedom along the 1D pore at sufficiently low temperatures,
typically below about 1/10 of the gap temperature between the ground and the first excited states of the
azimuthal motion. In 18 Å nanopores, the 4 He fluid film tubes show 1D phonon heat capacity below a few
hundred mK, which suggests the gap energy of the azimuthal phonon motion about a few Kelvins. In the
1D nanopores 28Å in diameter preplated with 1.4 atomic layers of 4 He, dilute 3 He adatoms show obviously
large heat capacity of a fluid. The 3 He film tubes show the heat capacity of the 2D Boltzmann gas above
the gap temperature of about 330 mK in the azimuthal motion. With decreasing the temperature, the 3 He
heat capacity shows a Schottky-like peak at about 1/3 of the gap temperature followed by an asymptotic
temperature-linear dependence at the lower temperatures. The peak indicates the dimensional crossover
from 2D at the higher temperatures to 1D at low temperatures. When the Fermi energy of the dilute
3
He film tubes is lower than the gap energy, a 1D degenerate Fermi fluid is realized at sufficiently lower
temperatures than the gap temperature.
Sorting category: Ad Quantum gases, fluids and solids
Keywords: Low-dimensional helium fluids, Bose fluid, degenerate Fermi fluid, nanopores
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