Electric-field-controlled interface strain coupling and non-volatile resistance switching of La_1-xBa_xMnO₃ thin films epitaxially grown on relaxor-based ferroelectric single crystals

We have fabricated magnetoelectric heterostructures by growing ferromagnetic La_1-xBa_xMnO₃ (x = 0.2, 0.4) thin films on (001)-, (110)-, and (111)-oriented 0.31Pb(In_1/2Nb_1/2)O₃-0.35Pb(Mg_1/3Nb_1/2)O₃-0.34PbTiO₃ (PINT) ferroelectric single-crystal substrates. Upon poling along the [001], [110], or [111] crystal direction, the electric-field-induced non-180° domain switching gives rise to a decrease in the resistance and an enhancement of the metal-to-insulator transition temperature TC of the films. By taking advantage of the 180° ferroelectric domain switching, we identify that such changes in the resistance and TC are caused by domain switching-induced strain but not domain switching-induced accumulation or depletion of charge carriers at the interface. Further, we found that the domain switching-induced strain effects can be efficiently controlled by a magnetic field, mediated by the electronic phase separation. Moreover, we determined the evolution of the strength of the electronic phase separation against temperature and magnetic field by recording the strain-tunability of the resistance [(ΔR/R)strain] under magnetic fields. Additionally, opposing effects of domain switching-induced strain on ferromagnetism above and below 197 K for the La_0.8Ba_0.2MnO₃ film and 150 K for the La_0.6Ba_0.4MnO₃ film, respectively, were observed and explained by the magnetoelastic effect through adjusting the magnetic anisotropy. Finally, using the reversible ferroelastic domain switching of the PINT, we realized non-volatile resistance switching of the films at room temperature, implying potential applications of the magnetoelectric heterostructure in non-volatile memory devices.