Quantum plasticity and dislocation-induced supersolidity

We suggest that below a certain temperature T J , the free energy for the creation of jog–antijog pairs in the dislocation network of solid He4 becomes negative. The underlying physical mechanism is the related liberation of vacancies which initiate Feynmanʹs permutation cycles in the bulk. Consequently, dislocations should deform, elongate and occupy an increasingly larger volume at low temperatures. This phenomenon should lead to a stiffening of the solid below T J and possibly to the appearance of a non-zero superfluid fraction at a second temperature T c ⩽ T J . To cite this article: J.-P. Bouchaud, G. Biroli, C. R. Physique 9 (2008).