Dependence of Spin Current Modulation on Stress-Mediated Magneto-Electric Coupling in Ferromagnetic Devices
Stress dependent micromagnetic modeling based on the Landau-Lifshitz-Gilbert equations evinces a remarkable relationship between uniaxial stress in ferromagnetic thin films and the pumped spin current density, and elucidates the influence of compressive and tensile stress on the static and dynamic magnetization of ferromagnetic thin films, and ferromagnetic (FM)/normal-metal (NM) heterostructures. Thus, the presence of deformation in the structure through a stress-mediated magnetoelectric-coupling triggers a change in the magnetic anisotropy field in ferromagnets via magnetostriction. In our micromagnetic simulations we considered yttrium iron garnet (YIG) as the FM layer and platinum (Pt) the NM for the spin-pumped current calculations, and the stress contribution was introduced as an additional term in the effective anisotropy constant which also comprised the magnetocrystalline and shape anisotropy contributions of YIG. Ostensibly, the dynamic control of the stress-dependent magnetization enables the tailoring of the magnetic anisotropy field to achieve the amplitude modulation of the pumped spin current density. The stress dependent behavior was identified by isolating the change in the anisotropy field associated with the magnetoelastic coupling of the YIG films along the easy magnetization axis. We also studied these effects on the FMR spectra of PE/YIG structures with the use of a microwave cavity and broadband setup. The mechanical deformation induced by the PE on the YIG film induced a change in the magnetic anisotropy, which directly affected the 4πMeff. Subsequently, the VISHE was measured on PE/YIG/Pt film showing a modulation of ∼8 μV. The predicted ability to dynamically modulate the pumped spin current density is anticipated to benefit multifarious spintronic applications.