Investigation of substrate-induced strain effects in La 0.7Ca0.15Sr0.15 MnO3 thin films using ferroelectric polarization and the converse piezoelectric effect

摘要

We have fabricated manganite film/ferroelectric crystal heterostructures by growing La0.7 Ca0.15 Sr0.15 MnO3 (LCSMO) films on ferroelectric 0.67Pb (Mg1/3 Nb2/3) O3 -0.33 PbTiO3 (PMN-PT) single-crystal substrates. The efficient mechanical coupling at the interface, originated from ferroelectric polarization or the converse piezoelectric effect in the PMN-PT substrate, gives rise to large changes in the strain state, electrical resistance, magnetoresistance, and insulator-to-metal transition temperature (TP) of the film. We interpreted all these changes in terms of substrate-induced strain, which modifies the tetragonal distortion of MnO6 octahedra and the electron-lattice coupling strength in the film. Quantitative relationships between TP and induced strain in the LCSMO film have been established.