Giant and universal magneto-electric coupling in soft materials

Magneto-electric coupling---the ability of a material to magnetize upon application of an electric field and conversely, to polarize under the action of a magnetic field---is rare and restricted to a rather small set of exotic hard crystalline materials.  In this work, we prove the existence of an overlooked strain mediated nonlinear mechanism that can be used to universally induce giant magneto-electric effect in all sufficiently soft dielectric materials. For soft polymer foams---which for instance may be used in stretchable electronics---we predict room-temperature magnetoelectric coefficients that are comparable to the best known (hard) composite materials created. We also argue, based on a simple quantitative model, that magneto-reception in some biological contexts (e.g. birds) most likely utilizes this very mechanism.