Strong enhancement of the direct magnetoelectric effect in strained ferroelectric-ferromagnetic thin-film heterostructures

The direct magnetoelectric (ME) effect resulting from polarization changes induced in a ferroelectric film by the application of a magnetic field to a ferromagnetic substrate is described using the nonlinear thermodynamic theory. We show that the ME voltage coefficient of heterostructures involving the Terfenol-D substrate and Pb(Zr1-xTix)O-3 (PZT) films may reach a giant value of 50 V cm(-1) Oe(-1). This remarkable feature is due to a favorable combination of considerable strain sensitivity of polarization and low electric permittivity in compressively strained PZT films. The theory also predicts a further dramatic increase in ME coefficients at the strain-induced transitions between different ferroelectric phases.