In ferroelectrics, the effect of domain wall motion on properties has been widely studied, but non-motional or stationary contributions from the volume of material within the domain wall itself has received less attention. Here we report the measurement of stationary domain wall contributions to permittivity in PbZr0.2 Ti0.8 O3 films. Studies of (001)-, (101)- and (111)-oriented epitaxial films reveal that (111)-oriented films, in which the motional domain wall contributions are frozen out, exhibit permittivity values approximately three times larger than the intrinsic response alone. This discrepancy can only be accounted for by considering a stationary contribution from the domain wall volume of the material that is 6-78 times larger than the bulk response, and is consistent with predictions of the enhancement of susceptibilities within 90° domain walls. This work offers new insights into the microscopic origin of dielectric enhancement and provides a pathway to engineer the dielectric response of materials.
Bibliographical noteFunding Information:
R.X. and L.W.M. would like to acknowledge the support of the National Science Foundation and the Nanoelectronics Research Initiative under grant DMR-1124696 and DMR-1149062. J.K. and L.W.M acknowledge support from the Office of Naval Research under grant number N00014-10-10525. A.R.D. and L.W.M. acknowledge support from the Army Research Office under grant W911NF-10-1-0482. Experiments were partially carried out in the Materials Research Laboratory Central Facilities, University of Illinois.