Giant caloric effects enhanced by the helix polarization at the 180° domain wall in tetragonal BaTiO3

Abstract

The electrocaloric and elastocaloric properties at the 180° domain wall in the tetragonal BaTiO3 are studied using the Landau-Ginzburg-Devonshire model as a function of the domain wall rotation angle α. The Ising-Bloch character is predicted at the 180° domain wall in tetragonal BaTiO3 under the flexoelectric effect. The electric field-induced adiabatic temperature change (ΔT E) which is induced by the Bloch-type polarization component depends on α, and a giant positive ΔT E appears at α = (π + 12n)/24 where n is an integer. The asymmetry of ΔT E is found around the Bloch-type domain wall. The Bloch-type polarization component has a little contribution to the stress-induced adiabatic temperature change. This calculation indicates a contribution of helix polarization at the domain wall on the caloric effects (CEs) in the ferroelectric materials.