90 degrees ferroelectric domain switching effect on interfacial strain mediated magnetoelectric coupling

The phenomena associated with strain-mediated multiferroic behavior have been quantitatively studied by combining synchrotron x-ray diffraction (XRD), ferromagnetic resonance (FMR) and macroscopic strain measurements (digital image correlation) in a magnetoelectric composite (Ni film on PZT substrate). The ferroelectric and piezoelectric strains have been studied by analyzing the evolution of x-ray patterns (peak intensities and shifts), while the magnetic response is studied by FMR (energy shift of the resonance), during in situ application of electrical voltage. Being given the intrinsic selective phase nature of XRD, the lattice strains have also been measured in the Ni film and have been found to be comparable to the macroscopic one (full transmission from the PZT substrate). The PZT strain has been successfully separated into two contributions, i.e. ferroelectric and lattice strains, the first one being five times higher than the second one. Moreover the last is itself composed of two sub-contributions: pure piezoelectric effect and ferroelectric strain in surrounding grains (strain transfer at grain boundaries). Finally, through in situ FMR measurements, we showed that the ferroelectric contribution to the strain-mediated magnetoelectric response is ten times higher than the pure piezoelectric one.