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Influence of the polarization anisotropy on the electrocaloric effect in epitaxial PMN-PT thin films

: Mietschke, Michael; Chekhonin, Paul; Molin, Christian; Gebhardt, Sylvia; Fähler, Sebastian; Nielsch, Kornelius; Schultz, Linda; Hühne, Ruben


Journal of applied physics 120 (2016), No.11, Art. 114102, 8 pp.
ISSN: 0021-8979
ISSN: 1089-7550
Deutsche Forschungsgemeinschaft DFG
SPP 1599; HU1726/3; Ferroic Cooling
Journal Article
Fraunhofer IKTS ()
anisotropy; cobalt compounds; electrodes

Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) compounds, which are typically used for high performance actuator applications due to their outstanding piezoelectric properties, show, in addition, a pronounced electrocaloric (EC) effect. The study of epitaxial films is a useful tool to analyze the correlation between the microstructure and EC properties in order to optimize the performance of these materials. Therefore, the 0.9PMN-0.1PT films were grown by a pulsed laser deposition on (001) as well as (111) oriented SrTiO3 single crystalline substrates using a La0.7Sr0.3CoO3 buffer as the bottom electrode and additional Au top electrodes. The structural properties determined by a high resolution X-ray and electron microscopy techniques indicated an undisturbed epitaxial growth. The anisotropy of the ferroelectric domain structure was investigated by a vertical and lateral piezoresponse force microscopy showing clear differences between the two orientations. A significant reduction of the thermal hysteresis was observed in the T-dependent polarization measurements for (111) oriented PMN-PT films, whereas the indirectly determined EC properties yield a maximum ΔT of around 15 K at 40 °C for a field of about 400 kV/cm for both film orientations.