Defect formation in inhomogeneous second-order phase transition: theory and experiment

The status quo in our understanding of defect formation during a rapid transition into the broken symmetry state in condensed matter and cosmology is discussed. An observation of vortex nucleation in neutron absorption experiments in superfluid ³He-B is interpreted in terms of defect formation during inhomogeneous cooling through T_c. Due to the temperature gradient in the locally heated region the superfluid-phase transition occurs as a propagating front. The theoretical considerations of vortex formation at the propagating front are based on works by Kibble–Volovik, Kopnin–Thuneberg, and Aranson–Kopnin–Vinokur (AKV).