Magnetoelectric Spin Wave Modulator Based On Synthetic Multiferroic Structure

We describe a spin wave modulator - spintronic device aimed to control spin wave propagation by an electric field. The modulator consists of a ferromagnetic film serving as a spin wave bus combined with a synthetic multiferroic comprising piezoelectric and magnetostrictive materials. Its operation is based on the stress-mediated coupling between the piezoelectric and magnetostrictive materials. By applying an electric field to the piezoelectric layer, the stress is produced. In turn, the stress changes the direction of the easy axis in the magnetostrictive layer and affects spin wave transport. We present experimental data on a prototype consisting of a piezoelectric [Pb(Mg_1/3Nb_2/3)O₃]_(1-x) -[PbTiO₃]_x substrate, and 30 nm layer of magnetostrictive Ni film, where the film is attached to a 30 nm thick Ni₈₁Fe₁₉ spin wave bus. We report spin wave signal modulation in Ni₈₁Fe₁₉ layer by an electric field applied across the piezoelectric layer. The switching between the spin wave conducting and non-conducting states is achieved by applying ±0.3 MV/m electric field. We report over 300% modulation depth detected 80 μm away from the excitation port at room temperature. The demonstration of the spin wave modulator provides a new direction for spin-based device development by utilizing an electric field for spin current control.