Strain-mediated Mott transition in Ca₂RuO₄ induced by a dc current

In a Mott insulator, the delicate balance among several competing energy scales gives rise to a plethora of ground states, which may be tuned into one another by pressure, electric field, photoexcitation among other perturbations. Owing to many degrees of freedom present in the system, understanding Mott transitions remains difficult. Recently, Ca₂RuO₄ has emerged as a new platform for studying the insulator-to-metal Mott transition. A dramatic change in its structural and optical properties across the phase boundary allows a multimodal approach to investigate the transition in space and time. Here, we report in situ transport, optical, and X-ray microscopy measurements on current-induced Mott transition in Ca₂RuO₄. We find that lattice strain plays a central role in this spatially-inhomogeneous transition, whose temporal evolution is characterized by local fluctuations in temperature. The present work clarifies important aspects of the current-induced Mott transition and provides insights into future applications that harness such electromagnetic control.