Flexomagnetism: Progress, challenges, and opportunities

Flexomagnetism refers to the higher order magneto-mechanical coupling, associating magnetic polarization with strain gradient. Although it is weak in bulk materials, the flexomagnetic effect in small-sized samples where the strain gradient could be remarkably large presents an opportunity for the efficient manipulation of magnetic performance in nanomaterials and advanced spintronic devices. In this article we share a state-to-the-art review on the progress, challenges, and opportunities for exploring flexomagnetism. The review starts with the narrow and general definitions of flexomagnetism with a focus on the intrinsic flexomagnetism and flexomagnetic response, respectively. Then we demonstrate the different types of strain gradient for inducing the flexomagnetic effect, the theoretical models at various scales for flexomagnetism, and the simulation/experimental progress on the manipulation of magnetic properties by using flexomagnetic effect. We then discuss the current controversies and challenges regarding the disagreements between experimental and computational results as well as the limitations of existing hypotheses. Lastly, we suggest some prospects for future research on flexomagnetism.