title: Superfluidity of grain boundaries in solid 4He.
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 approximately 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)10.1126/science.1130879] is not just a crack filled with superfluid.
authors.affiliation: Theoretische Physik, ETH Zürich, 8093 Zürich, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Pollet
authors.forename: M
authors.initials: M
authors.lastname: Boninsegni
authors.forename: A B
authors.initials: AB
authors.lastname: Kuklov
authors.forename: N V
authors.initials: NV
authors.lastname: Prokof'ev
authors.forename: B V
authors.initials: BV
authors.lastname: Svistunov
authors.forename: M
authors.initials: M
authors.lastname: Troyer