  Dynamic properties of NiFe thin films on PMN-PT piezoelectric substrate are
investigated using the spin-diode method. Ferromagnetic resonance (FMR) spectra
of microstrips with varying width are measured as a function of magnetic field
and frequency. The FMR frequency is shown to depend on the electric field
applied across the substrate, which induces strain in the NiFe layer. Electric
field tunability of up to 100 MHz per 1 kV/cm is achieved. An analytical model
based on total energy minimization and the LLG equation, with magnetostriction
effect taken into account, is developed to explain the measured dynamics. Based
on this model, conditions for strong electric-field tunable spin diode FMR in
patterned NiFe/PMN-PT structures are derived.
