Kibble-Zurek mechanism of Ising domains

The Kibble-Zurek mechanism (KZM) has been shown to be a successful theory in predicting the density of topological defects after phase transitions in many condensed matter systems with topological quantities. However, most fundamental non-topological Ising-type domains with two degenerate scalar order parameters had never been experimentally investigated within the framework of KZM, despite the ubiquity of Ising domains in condensed matter. The search for an ideal Ising system that enables easy imaging and comparison of domain populations across a wide range of cooling rates has proven challenging. we overcome these obstacles by carefully selecting and fabricating emerging materials that host structural 3D Ising domains (polar domains in BiTeI and ferro-rotation domains in NiTiO₃). Together with our innovative domain imaging techniques and efficient data analysis approaches, we experimentally demonstrated the validity of KZM for non-topological 3D Ising domains¹. Moreover, our results reveal an intriguing enhancement of the KZM exponent for transitions of non-topological quantities with long-range interactions, highlighting the significant role of possible long-range interactions in determining the KZM exponent in real systems. 1. K. Du, etc. Kibble–Zurek mechanism of Ising domains. Nat. Phys. 19, 1495–1501 (2023).