A non-perturbative study of bulk photovoltaic effect enhanced by an optically induced phase transition

TL;DR

This study explores how strong light-induced phase transitions in a correlated perovskite manganite can significantly enhance the bulk photovoltaic effect, revealing nonlinear responses and high photoresponsivity beyond traditional limits.

Contribution

It demonstrates the first non-perturbative analysis of bulk photovoltaic response in a strongly correlated system using real-time simulations, highlighting phase transitions as a control mechanism.

Findings

Photovoltaic current sharply increases at a photoinduced magnetic phase transition.

Peak photoresponsivity exceeds that of known ferroelectric oxides by orders of magnitude.

Phonon and spin contributions to photocurrent are comparable in magnitude.

Abstract

Solid systems with strong correlations and interactions under light illumination have the potential for exhibiting interesting bulk photovoltaic behavior in the non-perturbative regime, which has remained largely unexplored in the past theoretical studies. We investigate the bulk photovoltaic response of a perovskite manganite with strongly coupled electron-spin-lattice dynamics, using real-time simulations performed with a tight-binding model. The transient changes in the band structure and the photoinduced phase transitions, emerging from spin and phonon dynamics, result in a nonlinear current versus intensity behavior beyond the perturbative limit. The current rises sharply across a photoinduced magnetic phase transition, which later saturates at higher light intensities due to excited phonon and spin modes. The predicted peak photoresponsivity is orders of magnitude higher than other known ferroelectric oxides such as BiFeO$_3$. We disentangle phonon-and spin-assisted components to the ballistic photocurrent, showing that they are comparable in magnitude. Our results illustrate a promising alternative way for controlling and optimizing the bulk photovoltaic response through the photoinduced phase transitions in strongly-correlated systems.