The converse magnetoelectric (CME) coefficient of an artificial, multiferroic composite cylinder was determined for two interface boundary conditions; specifically epoxy-bonded and shrink-fit. The composite consists of two concentrically bonded rings with the inner and outer rings made from Terfenol-D and lead zirconate titanate, respectively. The diameter of the inner annulus was 25 mm, and the outer ring diameter was 30 mm. Electric fields ranging from 20 kV/m to 80 kV/m with AC components cycling at frequencies from 4 kHz to 50 kHz were applied for actuation of the composite. A magnetic bias field from 0 Oe to 2300 Oe was applied for enhancement of the CME coefficient. It has been found that the maximum CME for epoxy-bonded rings occurs at lower bias magnetic field than shrink-fitted rings. Resonance for the epoxy-bonded composite was found to be 36 kHz whereas the resonant frequency for the shrink-fit structure was 34 kHz. The maximum CME coefficients were approximately 535 mG/V at 100 Vpp and 330 mG/V at 400 Vpp for the epoxy-bonded and shrink-fit configurations, respectively.

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(Mg1/3Nb2/3)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.

Strain-mediated thin film multiferroics comprising piezoelectric/ferromagnetic heterostructures enable the electrical manipulation of magnetization with much greater efficiency than other methods; however, the investigation of nanostructures fabricated from these materials is limited. Here we characterize ferromagnetic Ni nanostructures grown on a ferroelectric PMN-PT substrate using scanning electron microscopy with polarization analysis (SEMPA) and micromagnetic simulations. The magnetization of the Ni nanostructures can be controlled with a combination of sample geometry and applied electric field, which strains the ferroelectric substrate and changes the magnetization via magnetoelastic coupling. We evaluate two types of simulations of ferromagnetic nanostructures on strained ferroelectric substrates: conventional micromagnetic simulations including a simple uniaxial strain, and coupled micromagnetic-elastodynamic simulations. Both simulations qualitatively capture the response of the magnetization changes produced by the applied strain, with the coupled solution providing more accurate representation.

Enhancing the magnetoelectric coupling in a strain-mediated multiferroic composite structure plays a vital role in controlling magnetism by electric fields. An enhancement of magnetoelastic coupling between ferroelectric single crystal (011)-cut [Pb(Mg1/3Nb2/3)O3](1-x)-[PbTiO3]x (PMN-PT, x≈ 0.30) and ferromagnetic polycrystalline Ni thin film through an interposed benzocyclobutene polymer thin film is reported. A nearly twofold increase in sensitivity of remanent magnetization in the Ni thin film to an applied electric field is observed. This observation suggests a viable method of improving the magnetoelectric response in these composite multiferroic systems.

Current research on artificial spin ice (ASI) systems has revealed unique hysteretic memory effects and mobile quasi-particle monopoles controlled by externally applied magnetic fields. Here, we numerically demonstrate a strain-mediated multiferroic approach to locally control the ASI monopoles. The magnetization of individual lattice elements is controlled by applying voltage pulses to the piezoelectric layer resulting in strain-induced magnetic precession timed for 180° reorientation. The model demonstrates localized voltage control to move the magnetic monopoles across lattice sites, in CoFeB, Ni, and FeGa based ASI's. The switching is achieved at frequencies near ferromagnetic resonance and requires energies below 620 aJ. The results demonstrate that ASI monopoles can be efficiently and locally controlled with a strainmediated multiferroic approach.