Flexoelectricity and Twins in LaAlO₃

Flexoelectricity in complex oxides has recently garnered much interest due to its ubiquity, intrinsic scaling at the nanoscale, and device applications. Although this has resulted in a dramatic increase in the number of publications on this phenomenon, an abundance of fundamental questions persists. In particular, the role of microstructure on the flexoelectric response of oxides is scantly considered in the existing literature. Twinned oxides are well-poised to elucidate this question because they naturally bridge the gap between single crystals and polycrystalline ceramics. In this work, a dynamic mechanical analyzer in a three-point bending configuration was used to study the flexoelectric response of {100}_pc-LaAlO₃ with lamellar twin microstructures as a function of temperature. We found the flexoelectric response of LaAlO₃ is dominated by its twinned microstructure and tunable by two orders of magnitude via changing the number of twins, domain wall orientation, and domain wall mobility.