The localized temperature-dependent piezoelectric response of ferroelectric barium strontium titanate (BST) thin films is studied using an electro-thermal (ET) nanoprobe. The ET probe provides independent electrical and thermal excitation to a nanometer-scale volume of the specimen and is capable of detecting the phase transition temperature of the BST thin films. The piezoresponse measured by the ET probe follows the temperature dependence of the piezoelectric constant, whereas with bulk heating the response follows the temperature dependence of the spontaneous polarization. The observed differences stem from the localized inhomogeneous electro-thermal field distribution at the specimen.
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation (NSF) under Grant No. 0960232. J.K. and L.W.M. acknowledge support from the Office of Naval Research (ONR) under Grant No. N00014-10-10525. A.R.D. and L.W.M. acknowledge support from the (U.S.) Army Research Office (USARO) under Grant No. W911NF-10-1-0482. The authors thank Dr. Scott MacLaren at FSMRL Central Facilities for his assistance with part of the AFM work.