Reversible tuning of lattice strain in epitaxial SrTiO3/La0.7Sr0.3MnO3 thin films by converse piezoelectric effect of 0.72Pb(Mg1/3Nb2/3)O3−0.28 PbTiO3 substrate

Abstract

Thin SrTiO3/La0.7Sr0.3MnO3 (STO/LSMO) films of 30 nm thickness were epitaxially grown on a (001) Pb(Mg1/3Nb2/3)O3−28 mol % PbTiO3 piezoelectric single-crystalline plate and investigated by means of wide-angle x-ray scattering in situ under the influence of a direct current electric field with strength E up to ±18 kV/cm. The strain s in the films could by tuned dynamically due to a dominant converse piezoelectric effect of the substrate. The coefficient of coupling between electric field-induced strain alteration of the substrate and the buffer film (LSMO) is approximately 0.75, whereas for the substrate and top films (STO) it is about 0.35 related to a normalized strain alteration of the substrate of 1.