QFS2016 Book of Abstracts

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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