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Abstracts
P1.35
Intertwined superfluid and density wave order in two dimensional
4
He
Ny´eki J´an(1), Phillis Anastasia(1), Ho Andrew(1), Lee Derek(2), Coleman
Piers(1,3), Parpia Jeevak(4), Cowan Brian(1), Saunders John(1)
1) Department of Physics, Royal Holloway University of London, Egham, Surrey,
TW20 0EX, U.K.
2) Department of Physics, Blackett Laboratory, Imperial College London, London
SW7 2AZ, U.K.
3) Center for Materials Theory, Department of Physics and Astronomy, Rutgers
University, Piscawatay, NJ 08854, USA
4) Department of Physics, Cornell University, Ithaca, NY 14853, USA
Department of Physics, Royal Holloway, University of London, UK We review our
torsional oscillator measurements which find four distinct regimes of anomalous
superfluid response in the second layer of
4
He adsorbed on graphite, over a
coverage range near third layer promotion. Our identification of a new quantum
phase is consistent with heat capacity measurements. Interestingly the most
recent path-integral Monte Carlo simulations find no evidence for second layer
commensurate solid. Our data identifies the new phase to be an unconventional
emergent state in which superfluidity and solidity are quantum entangled. We
also find the superfluid response persists up to third layer promotion at which
the energy scale governing superfluid onset vanishes.
P1.36
4
He confined in narrow nanopores
Leandra Vranjes Markic(1), Henry R. Glyde(2)
1) University of Split, Faculty of Science, Rudera Boˇskovica 33, 21000 Split,
Croatia
2) Department of Physics and Astronomy, University of Delaware, Newark,
Delaware 19716-2593, USA
Path integral Monte Carlo (PIMC) and diffusion Monte Carlo calculations of
4
He confined in narrow nanopores are presented. Superfluid fraction and the
one-body density matrix (OBDM) are obtained with the goal to determine the
effective dimensions of
4
He in the nanopore.
The PIMC superfluid fraction and OBDM scale as a 1D Luttinger Liquid at
extremely small liquid pore diameters only, where the liquid atoms form a 1D
line at the center of the pore, while for larger pores, crossover to 2D behaviour
is obtained [2]. The effects of disorder are estimated for selected nanopore sizes
and densities.
1. L. Vranjes Markic and H. R. Glyde, Phys. Rev. B92, 064510 (2015)
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