Magneto-electric and strain coupling in ferromagnetic manganite thin films grown on ferroelectric substrates

We study the magneto-electric coupling in La$_{0.67}$Ca$_{0.33}$MnO$_{3}$ (LCMO) and La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO) thin films with thickness between 5 and 20 nm grown on ferroelectric BaTiO$_{3}$ (BTO) or Pb(Mg$_{0.33}$Nb$_{0.67}$)$_{0.72}$Ti$_{0.28}$O$_{3}$ (PMNT) single crystal substrates. We measure the temperature, magnetic and electric field dependent magnetization and magnetoresistance of the manganite thin films. In bulk, LCMO is more prone to disorder induced phase segregation and a metal- insulator transition than LSMO. Nevertheless, the substrate- strain induced changes in LSMO have been more extensively reported. We report large magnetoresistance changes of LCMO thin films corresponding to the structural phase transitions of the BTO substrate.