Parametric Excitation of Spin Waves by Voltage-Controlled Magnetic Anisotropy

A theory of parametric excitation of spin waves (SWs) in ultrathin ferromagnetic strips by a microwave electric field is developed. The excitation uses the effect of voltage-controlled magnetic anisotropy in ferromagnet-dielectric heterostuctures. The characteristic values of the electric field necessary for parametric excitation of propagating SWs of 5-10 GHz frequency in Fe/MgO structure are found to be 0.1-1.5 V/nm. The minimum excitation threshold is achieved in narrow strip (strip width w(x) similar to 10-20 nm) for relatively long dipole-dominated SWs. In wider strips (w(x) greater than or similar to 100 nm) electric parametric pumping excites mostly short exchange-dominated SWs having higher excitation thresholds, but substantially wider range of possible SW frequencies.