Evaluating non-intrinsic contribution in flexoelectric measurements

The characterization of the flexoelectric coefficient is a fundamental issue for the studies of the flexoelectric effect, which describes the coupling between strain gradient and polarization. However, the contribution from non-intrinsic flexoelectricity cannot be ignored in the flexoelectric measurements, bringing challenges for the determination of intrinsic flexoelectric coefficients. In this work, we propose a non-intrinsic flexoelectric factor to evaluate the non-intrinsic flexoelectric contributions to the measured coefficient, based on the crystal-orientation-dependent flexoelectric coefficients measured by cantilever-bending method. The cubic magnesium oxide single crystals with different surface statuses are chosen to obtain the effective flexoelectric coefficients through the cantilever-bending method and first-principles. The results verify the effectiveness of the proposed non-intrinsic flexoelectric factor. This work provides an effective way to evaluate the non-intrinsic flexoelectric contributions in flexoelectric measurements.