Superfluidity of Grain Boundaries in Solid 4He

L Pollet
M Boninsegni
A Kuklov
Nikolai Prokof'ev, University of Massachusetts - Amherst
Boris Svistunov, University of Massachusetts - Amherst
M Troyer

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This is the pre-published version harvested from ArXiv. The published version is located at http://prl.aps.org/abstract/PRL/v98/i13/e135301

Abstract

By large-scale quantum Monte Carlo simulations we show that grain boundaries in 4He crystals are generically superfluid at low temperature, with a transition temperature of the order of ∼0.5  K at the melting pressure; nonsuperfluid grain boundaries are found only for special orientations of the grains. We also find that close vicinity to the melting line is not a necessary condition for superfluid grain boundaries, and a grain boundary in direct contact with the superfluid liquid at the melting curve is found to be mechanically stable and the grain-boundary superfluidity observed by Sasaki et al. [Science 313, 1098 (2006)] is not just a crack filled with superfluid.