Chirality in solids is attracting growing attention as a potential ferroic order, yet virtually no paradigmatic example of a soft-mode achiral-to-chiral phase transition has been firmly established to date. Here we identify ferroelectric bubble domains as a model system that undergoes a strain-driven achiral-to-chiral transition exhibiting the hallmarks of spontaneous symmetry breaking. Using second-principles atomistic simulations, we uncover chiral phonon modes in ferroelectric/dielectric superlattices that soften under epitaxial strain following textbook soft-mode behaviour. The transition is accompanied by a change in topological character, highlighting an interplay between chirality and topology in these systems. This work provides a concrete step towards establishing chirality as a genuine ferroic order in solids.
@article{arxiv.2510.17573,
title = {Chiral soft mode transition driven by strain in ferroelectric bubble domains},
author = {Urmimala Dey and Natalya S. Fedorova and Jorge Íñiguez-González and Hugo Aramberri},
journal= {arXiv preprint arXiv:2510.17573},
year = {2025}
}