Dynamics of a Persistent Insulator-to-Metal Transition in Strained Manganite Films

Abstract

Transition metal oxides possess complex free-energy surfaces with competing degrees of freedom. Photoexcitation allows shaping of such rich energy landscapes. In epitaxially strained La[subscript 0.67]Ca[subscript 0.33]MnO[subscript 3], optical excitation with a sub-100-fs pulse above 2 mJ/cm[superscript 2] leads to a persistent metallic phase below 100 K. Using single-shot optical and terahertz spectroscopy, we show that this phase transition is a multistep process. We conclude that the phase transition is driven by partial charge-order melting, followed by growth of the persistent metallic phase on longer timescales. A time-dependent Ginzburg-Landau model can describe the fast dynamics of the reflectivity, followed by longer timescale in-growth of the metallic phase.