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DF: Fachverband Dielektrische Festkörper

DF 3: Dielectric and ferroelectric thin films 2

DF 3.5: Talk

Monday, March 14, 2011, 16:30–16:50, MÜL Elch

Growth of epitaxial multiferroic tunnelling heterostructures by pulsed laser deposition — •Silvana Goetze, Daniel Pantel, Marin Alexe, and Dietrich Hesse — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany

A multiferroic tunnelling heterostructure is a system of a thin ferroelectric film sandwiched between ferromagnetic electrodes, which could be applied in next generation of storage devices. Furthermore, they can be used to investigate electroresistance and magnetoelectric effects at interfaces. Here, we report on the growth of such structures by pulsed laser deposition. We have chosen PbZr_0.2Ti_0.8O₃ (PZT) as the ferroelectric layer and La_0.7Sr_0.3MnO₃ (LSMO) as the ferromagnetic bottom and top electrode grown on SrTiO₃ (100) (STO) substrate. For tunnelling junctions a low resistivity and a low surface roughness of the LSMO bottom electrode is crucial. Therefore, we optimized the growth conditions (temperature, oxygen pressure, laser energy, laser frequency) accordingly. Transmission electron microscopy images demonstrate the epitaxial growth of LSMO and PZT. Both are fully strained to the STO substrate as can be seen by x-ray diffraction. Hence, thicker PZT films show good ferroelectric hysteresis loops with high remnant polarization. Piezo-response force microscopy proves the ferroelectric behaviour for thinner PZT films.