Epitaxial growth and interface strain coupling effects in manganite film/piezoelectric-crystal multiferroic heterostructures

Abstract We constructed multiferroic structures by epitaxially growing colossal magnetoresistive La 0.7 Sr 0.3 MnO 3 (LSMO) thin films on piezoelectric single-crystal substrates of composition 0.67Pb(Mg 1/3 Nb 2/3 )O 3 –0.33PbTiO 3 (PMN-PT). Due to the efficient elastic coupling at the interface, the electric-field-induced piezoelectric strain ( ɛ piezo ) in the PMN-PT substrate is effectively transferred to the LSMO film, giving rise to a remarkable modulation of the lattice strain, resistivity, and Curie temperature T C of the LSMO film. Particularly, it was found that the magnetic field has an opposite effect on the strain-tunability of resistivity above and below T C . Moreover, we found that the resistivity of the film is most sensitive to ɛ piezo near T C and becomes less sensitive to ɛ piezo when the temperature is lower or higher than T C . These, together with the well fitted resistivity data into a phenomenological model based on coexisting phases, demonstrate that the phase separation is crucial to understand the strain-mediated multiferroic properties in manganite film/PMN-PT structures.