Direct Observation of Large Flexoelectric Bending at the Nanoscale in Lanthanide Scandates

There is a growing interest in the flexoelectric effect, since at the nanoscale it is predicted to be very large. However, there have been no direct observations of flexoelectric bending consistent with current theoretical work that implies strains comparable to or exceeding the yield strains of typical materials. Here we show a direct observation of extraordinarily large, two-dimensional reversible bending at the nanoscale in dysprosium scandate due to the converse flexoelectric effect, with similar results for terbium and gadolinium scandate. Within a transmission electron microscope, thin features bend up to 90° with radii of curvature of about 1 μm, corresponding to very large nominal strains. Analysis including independent experimental determination of the flexoelectric coefficient is semiquantitatively consistent with interpreting the results as due to flexoelectricity. These results experimentally demonstrate large flexoelectric bending at the nanoscale.