Volume 84, Number 4, November 2008
Article Number 40003
Number of page(s) 5
Section General
Published online 30 October 2008
EPL, 84 (2008) 40003
DOI: 10.1209/0295-5075/84/40003

Structure of metastable 2D liquid helium

V. Apaja1 and M. Saarela2

1   Department of Physics, University of Jyväskylä - P.O. Box 35, FIN-40014, Finland, EU
2   Department of Physical Sciences, University of Oulu - P.O. Box 3000, FIN-90014, Finland, EU

received 15 July 2008; accepted in final form 3 October 2008; published November 2008
published online 30 October 2008

We present diffusion Monte Carlo (DMC) results on a novel, superfluid phase in two-dimensional 4He at densities higher than 0.065 Å-2, which is very close to the freezing density. The new phase has anisotropic, hexatic orbital order, but the single-particle density remains constant. By increasing density the hexatic superfluid forms a metastable state, which lies above the crystal ground state in energy. This implies that the liquid-solid phase transition takes place in two stages: a second-order phase transition from the isotropic superfluid to the hexatic superfluid, followed by a first-order transition that localizes atoms into the triangular crystal order.

02.70.Ss - Quantum Monte Carlo methods.

© EPLA 2008