Light-induced long-lived metallic phase in an excitonic insulator studied by angle-resolved photoemission

Non-equilibrium states in materials are usually studied in the ultrafast time domain. However, a recent report on the excitonic insulator Ta2NiSe5 used light pulses to induce a low-resistance state that can last for several hours or days. To date, little is known on the electronic structure of this novel metallic state. We investigate here the effect of light pulses on the electronic bands of Ta2NiSe5 by using Angle-Resolved Photoemission Spectroscopy (ARPES) using synchrotron light as a probe and infrared light pulses to trigger the metastable state, and report on our findings.