Laser Model for Fast Crystallization of Overcooled He

A recent experiment has shown that, in the bcc-hcp transition of solid ⁴He. the new phase is nucleated at many sites inside the original crystal. Strongly reminiscent of a martensitic transition, the transition is reversible. For this transition, we consider a possible microscopic mechanism, which was earlier applied to martensitic transitions in metallic alloys. We assume that the phase boundary is coherent, and atomic displacements are reversible and do not exceed a unit cell size during the transition. A double-well model is applied to the description of the boundary. The parameters of the boundary are related to the crystal lattice parameters