Long-Range Electric Field Control of Permalloy Layers in Strain-Coupled Composite Multiferroics
Michelle Elizabeth Jamer, Colin R. Rementer, Anthony Barra, Alexander J Grutter, Kevin Fitzell, Daniel Bernard Gopman, Julie A. Borchers, Gregory P. Carman, Brian J Kirby, Jane P. Chang
Artificial composite multiferroic materials can be created by interfacing magnetostrictive and piezoelectric materials, allowing for electric field control of magnetic properties. For multilayer device applications, addition of weakly magnetostrictive layers is a potentially important means of tuning functionality. For such a device, the lengthscale over which weakly magnetostrictive layer(s) can be coupled to an applied electric field is of critical importance. In this work, we use polarized neutron reflectometry to characterize this distance for a model composite multiferroic multilayer system (PMN-PT/galfenol/permalloy). For a superlattice more than 100 nm thick, we observe that the magnetizations of all layers rotate coherently with applied electric field. Further, we observe electric field induced rotation across the entirety of a 46 nm permalloy layer anchored by a single galfenol interface. The confirmation of long-range magnetic coupling in these strain-coupled multiferroic composites opens extensive opportunities for designer technological applications.