Strain-dependent ferroic properties of doped LaMO3(M=Mn or Co) and BiFeO3

Elastic strain at epitaxially grown interfaces provides an efficient coupling mechanism in two-phase multiferroics: piezoelectric or magnetostrictive strain arising from application of an electric or a magnetic field is transferred readily between the components. We employ a piezoelectric single-crystalline substrate to apply reversible biaxial strain to epitaxially grown magnetic or ferroelectric films and study the strain response of their ferroic properties. The relaxor-based 0.72PbMg1/3Nb2/3O3 -0.28PbTiO3(001) (PMN-PT) proved to be a favourable piezo-substrate with large, reversible, uniform in-plane strain which shows little temperature dependence. The magnetization vs. strain of doped LaMO3 (M=Mn or Co) phases has been studied. It reveals the impact of the strain-induced tetragonal lattice distortion on the ferromagnetic double exchange and the magnetic moment of Co ions that leads to moderate or large magnetization modulation. Further, the strain dependence of ferroelectric switching has been investigated for multiferroic BiFeO3. It displays a large response of unexpected sign attributed to a strain influence on kinetics.