Photoinduced insulator-to-metal dynamics in strained NdNiO3 ultrathin films

Epitaxial rare-earth nickelate thin films are ideally suited for the study and control of electronic correlations associated with the insulator-to-metal phase transition since strain can be precisely controlled. We investigate picosecond conductivity dynamics of strained NdNiO3 utilizing time-domain terahertz spectroscopy. Starting from the insulating phase, photoexcitation results in a conductivity increase towards the metallic state. The dynamics consist of a fast ~1ps increase accompanied by a slower increase occurring over tens of picoseconds. These results will be compared to those obtained on the vanadates where the slow rise time is ascribed to nucleation and growth of the metallic phase.