We examine the discontinuous first-order superfluid 3He A to B transition in the vicinity of the polycritical point (2.232 mK and 21.22 bar). We find path-dependent transitions: cooling at fixed pressure yields a well defined transition line in the temperature-pressure plane, but this line can be reliably crossed by depressurizing at nearly constant temperature after transiting Tc at a higher pressure. This path dependence is not consistent with any of the standard B-phase nucleation mechanisms in the literature. This symmetry breaking transition is a potential simulator for first order transitions in the early universe.
@article{arxiv.2012.14044,
title = {Path-Dependent Supercooling of the $^3$He Superfluid A-B transition},
author = {Dmytro Lotnyk and Anna Eyal and Nikolay Zhelev and Abhilash Sebastian and Yefan Tian and Aldo Chavez and Eric Smith and John Saunders and Erich Mueller and Jeevak Parpia},
journal= {arXiv preprint arXiv:2012.14044},
year = {2021}
}