Leggett's bound for amorphous solids

Giulio Biroli (1) , Bryan Clark (2) , Laura Foini (3) , Francesco Zamponi (3)

1 IPHT - Institut de Physique Théorique - UMR CNRS 3681
2 Princeton University
3 LPTENS - Laboratoire de Physique Théorique de l'ENS [École Normale Supérieure]

We investigate the constraints on the superfluid fraction of an amorphous solid following from an upper bound derived by Leggett. In order to accomplish this, we use as input density profiles generated for amorphous solids in a variety of different manners including by investigating Gaus-sian fluctuations around classical results. These rough estimates suggest that, at least at the level of the upper bound, there is not much difference in terms of superfluidity between a glass and a crystal characterized by the same Lindemann ratio. Moreover, we perform Path Integral Monte Carlo simulations of distinguishable Helium 4 rapidly quenched from the liquid phase to very lower temperature, at the density of the freezing transition. We find that the system crystallizes very quickly, without any sign of intermediate glassiness. Overall our results suggest that the experimental observations of large superfluid fractions in Helium 4 particles after a rapid quench correspond to samples evolving far from equilibrium, instead of being in a stable glass phase. Other scenarios and comparisons to other results on the super-glass phase are also discussed.

Domaines: Physique [physics]

Giulio Biroli, Bryan Clark, Laura Foini, Francesco Zamponi. Leggett's bound for amorphous solids. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2011, 83, pp.094530. ⟨10.1103/PhysRevB.83.094530⟩. ⟨cea-02524971⟩