Flexocaloric effects in ferroic materials

Flexoferroic materials are materials with interplay between a ferroic property such as polarization or magnetization and the gradient of a mechanical strain. Flexoelectricity is one of the most studied effects due to the fact that this effect is allowed by symmetry in any material. We develop the thermodynamics of the flexoferroic materials and apply the results to study flexocaloric effects in ferroic solids. Flexocaloric effect is the reversible component of the thermal response of a solid to deformation bending (in general inhomogeneous straining). The two limits of interest correspond to bending performed in isothermal and adiabatic conditions. In the first case, the flexocaloric effect is quantified by the change of entropy of the material, which is related to the heat exchanged with the surroundings. In the second case it is quantified by the corresponding change of temperature. Recently a number of studies have considered the possibility of a flexocaloric effect in ferroelectric materials. We address the nature of this phenomenon in a variety of ferroic materials.