Electric field tuning of magnetic domains in permalloy thin films using elastic coupling with ferroelectric PZT bilayers*

We are investigating electric field controlled magnetic domain motion in permalloy films deposited on Pb(Zr$_{x}$Ti$_{(1-x)}$) O$_{3}$ (PZT) bilayers. Previously, we have shown that bilayered heterostructures consisting of a tetragonal PbZr$_ {0.3}$Ti$_{0.7}$O$_{3}$ film (70 nm) deposited on a rhombohedral PbZr$_{0.7}$Ti$_{0.3}$O$_{3}$ (70 nm) display large ferroelastic domains in the top tetragonal PZT layer (Adv. Mat. 21, 3497, 2009). The reversible non-volatile twin boundary motion in this layer can serve as a basis for inducing controlled strain on magnetic thin films deposited on top. We find that permalloy films (50 nm) sputtered on top of the ferroelastic layer exhibit out-of-plane magnetization whose domains can be imaged by magnetic force microscopy (MFM). Voltage pulses are applied between patterned pads of the permalloy film and the bottom electrode underneath the PZT bilayer. This results in different twin configurations in the tetragonal PZT layer, which in turn leads to changes in magnetic domains in the permalloy film as monitored by MFM.