Nanoscale domain structure evolution and magnetoelectric coupling for PMN-33PT/Terfenol-D multiferroic composite

Multiferroic composites of Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) (PMN-xPT) single crystal and Tb0.3Dy0.7Fe2 (Terfenol-D) possess strong magnetoelectric (ME) coupling at room temperature and hold promises as magnetic field sensors, and energy harvesting devices, etc. The nanoscale domain structure evolution upon the applied magnetic field determines the ME coupling. Via introducing of the PLM (Polarized Light Microscope) into the commercialized Piezoelectric Force Microscope (PFM) (named as PLM-PFM system), in-situ observations of domain structure evolution and ME coupling are investigated for [001]-oriented PMN-33PT/Terfenol-D composites. Upon the magnetic loadings, via strain transfer, domains of orthorhombic (O) phase first expands in area, and then a phase transition from O to monoclinic (M) phase takes place in PMN-33PT. Correspondingly, modulation of the electric field-induced displacement (or the inverse piezoelectric response) can be achieved by the magnetic field. Finite-element simulations are performed to calculate the magnetic field-induced displacement, which demonstrate its dependence on the piezomagnetic coefficient of Terfenol-D. The results provide insight into the magnetic field induced domain switching in nanoscale and magnetoelectric coupling for the PMN-PT/Terfenol-D multiferroic composites.