title: Large elasto-optic effect and reversible electrochromism in multiferroic BiFeO3.
abstract: The control of optical fields is usually achieved through the electro-optic or acousto-optic effect in single-crystal ferroelectric or polar compounds such as LiNbO3 or quartz. In recent years, tremendous progress has been made in ferroelectric oxide thin film technology-a field which is now a strong driving force in areas such as electronics, spintronics and photovoltaics. Here, we apply epitaxial strain engineering to tune the optical response of BiFeO3 thin films, and find a very large variation of the optical index with strain, corresponding to an effective elasto-optic coefficient larger than that of quartz. We observe a concomitant strain-driven variation in light absorption--reminiscent of piezochromism--which we show can be manipulated by an electric field. This constitutes an electrochromic effect that is reversible, remanent and not driven by defects. These findings broaden the potential of multiferroics towards photonics and thin film acousto-optic devices, and suggest exciting device opportunities arising from the coupling of ferroic, piezoelectric and optical responses.
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: D
authors.initials: D
authors.lastname: Sando
authors.affiliation: Department of Physics and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: Yurong
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Theoretical Materials Physics, Université de Liège, B-5, B-4000 Sart-Tilman, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Bousquet
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: C
authors.initials: C
authors.lastname: Carrétéro
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: V
authors.initials: V
authors.lastname: Garcia
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: S
authors.initials: S
authors.lastname: Fusil
authors.affiliation: Thales Research and Technology France, 1 Avenue Augustin Fresnel, 91767 Palaiseau, France.
authors.forename: D
authors.initials: D
authors.lastname: Dolfi
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Barthélémy
authors.affiliation: Theoretical Materials Physics, Université de Liège, B-5, B-4000 Sart-Tilman, Belgium.
authors.forename: Ph
authors.initials: P
authors.lastname: Ghosez
authors.affiliation: Department of Physics and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: L
authors.initials: L
authors.lastname: Bellaiche
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: M
authors.initials: M
authors.lastname: Bibes