Critical dislocation speed in helium-4 crystals

Critical dislocation speed in helium-4 crystals

Search for Dislocation Free Helium 4 Crystals

The giant plasticity of [Formula: see text]He crystals has been explained as a consequence of the large mobility of their dislocations. Thus, the mechanical properties of dislocation free crystals should be quite different from those of usual ones. In 1996-1998, Ruutu et al. published crystal growth studies showing that, in their helium 4 crystals, the density of screw dislocations along the c-...

Luttinger liquid in the core of a screw dislocation in helium-4.

On the basis of first-principles Monte Carlo simulations we find that the screw dislocation along the hexagonal axis of an hcp 4He crystal features a superfluid (at T-->0) core. This is the first example of a regular quasi-one-dimensional supersolid--the phase featuring both translational and superfluid orders, and one of the cleanest cases of a Luttinger-liquid system. In contrast, the same ty...

New quantum states in helium crystals

Large metallic cylinders with a mass of several tons have been cooled to liquid helium temperatures and recently down to T 100 mK leading to the most sensitive gravitational wave detector (NAUTILUS). The sensitivity is still not enough to detect waves from distances so large that the number of events becomes several per year. Cooling spherical detectors with a mass around 100 tons to temperatur...

Strongly Nonlocal Dislocation Dynamics in Crystals

We consider the equation vt = Lsv −W ′(v) + σε(t, x) in (0,+∞)×R, where Ls is an integro-differential operator of order 2s, with s ∈ (0, 1), W is a periodic potential, and σε is a small external stress. The solution v represents the atomic dislocation in the Peierls–Nabarro model for crystals, and we specifically consider the case s ∈ (0, 1/2), which takes into account a strongly nonlocal elast...