Insulator-to-Metal Transition Induced by Oxygen Deficiency in a Mott Insulator

Chemical tuning can be used to drive Mott insulators into a critical regime straddling the local-to-itinerant magnetic moment, in which emergent states like unconventional superconductivity or correlated topology are predicted to occur. In this talk, I will present our approach to reaching this crossover region in a Mott insulator oxyarsenide by tuning the oxygen content using both time-dependent and temperature-dependent annealing in reducing atmospheres. We have successfully demonstrated that oxygen deficiency indeed drives the system through this crossover, as indicated by resistivity measurements going from insulating to metallic behavior. A faster decrease in resistivity is observed with higher annealing temperatures and longer annealing times.