Orientation dependence of the electrocaloric effect in multilayers

A phenomenological thermodynamic model is presented to investigate the effects of the orientation and the relative thickness of SrTiO3 layer on the electrocaloric effect in PbTiO3/SrTiO3 multilayers. Theoretical calculations show that complete polarization suppression and a large electrocaloric effect take place at the critical relative thickness of SrTiO3 layer of 46%, 33%, and 30% for the (001), (110), and (111) oriented PbTiO3/SrTiO3 multilayers respectively, not occuring at the critical relative thickness of 63%, 50%, and 46% reported by Wu et al. [H.P. Wu, A.P. Liu, L.Z. Wu, S.Y. Du, Appl. Phys. Lett. 93 (2008) 242909]. Moreover, (111) oriented multilayers have the largest electrocaloric effect which is different from that of BaTiO3/SrTiO3 multilayers where (110) oriented multilayers have the largest electrocaloric effect. Consequently, the electrocaloric effect of PbTiO3/SrTiO3 multilayers can be adjusted by the orientation and the relative thickness of SrTiO3 layer.