Anomalous circular bulk photovoltaic effect in BiFeO<sub>3</sub> thin films with stripe-domain pattern.

Knoche, David S; Steimecke, Matthias; Yun, Yeseul; Mühlenbein, Lutz; Bhatnagar, Akash · Nat Commun · 2021

basic_science · Level V

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Abstract

Multiferroic bismuth ferrite, BiFeO<sub>3</sub>, offers a vast landscape to study the interplay between different ferrroic orders. Another aspect which is equally exciting, and yet underutilized, is the possibility of large-scale ordering of domains. Along with symmetry-driven bulk photovoltaic effect, BiFeO<sub>3</sub> presents opportunities to conceptualize novel light-based devices. In this work, we investigate the evolution of the bulk photovoltaic effect in BiFeO<sub>3</sub> thin films with stripe-domain pattern as the polarization of light is modulated from linear to elliptical to circular. The open-circuit voltages under circularly polarized light exceed ± 25 V. The anomalous character of the effect arises from the contradiction with the analytical assessment involving tensorial analysis. The assessment highlights the need for a domain-specific interaction of light which is further analyzed with spatially-resolved Raman measurements. Appropriate positioning of electrodes allows observation of a switch-like photovoltaic effect, i.e., ON and OFF state, by changing the helicity of circularly polarized light.