Flexoelectricity in metals

Flexoelectricity is an electromechanical phenomenon that, unlike piezoelectricity, is present in any material. While the largest flexoelectric response is observed in ferroelectrics and related materials, its manifestations in various other materials are of great interest for a broad scope of scientific and industrial tasks. Here, we provide a simple theoretical model for flexoelectricity in metals. This is done in terms of continuum mechanics. Estimates for aluminum are provided, and guidelines for an experimental detection of the phenomenon are formulated. The magnitude for the flexoelectric effect in metals is found to be comparable with that in high-k dielectrics, which makes metals just as good as other materials for applications in flexoelectric sensing and energy harvesting. Besides, in metals, flexoelectricity may be easier to interpret because it is predicted to be free of surface contributions.