Striped nanoscale phase separation at the metal–insulator transition of heteroepitaxial nickelates

Probing the evolution of mixed-phase states in materials offers unique insights into the microscopic mechanism of phase transitions. Here, Mattoni et al. report imaging of nanoscale formation and growth of insulating domains across the metal-insulator transition in NdNiO3thin films, uncovering a rich interplay between structural and electronic degrees of freedom.