Electrical detection of parallel parametric amplification and attenuation in Y3Fe5O12\mathrm{Y}_3\mathrm{Fe}_5\mathrm{O}_{12}/Pt\mathrm{Pt} bilayer disk

We report a systematic quantitative evaluation of parametric amplification gain of magnetization dynamics in ytirrium iron garnet ($\mathrm{Y}_3\mathrm{Fe}_5\mathrm{O}_{12}$) thin disk via a.c. spin pumping and inverse spin Hall effect. We demonstrate its signature phase-dependence where amplification and attenuation occur every $\frac{\pi}{2}$ phase shift of the input signal. The results also show the pump-power dependence of the gain that is explained well by our theoretical model. Finally, the optimal conditions for the amplification is investigated by measuring the magnetic field dependence, where we find the highest gain of 11.4 dB.Comment: 6 pages, 3 figures, 14 panel

Switching of magnon parametric oscillation by magnetic field direction

Parametric oscillation occurs when the resonance frequency of an oscillator is periodically modulated. Owing to time-reversal symmetry breaking in magnets, nonreciprocal magnons can be parametrically excited when spatial-inversion symmetry breaking is provided. This means that magnons with opposite propagation directions have different amplitudes. Here we demonstrate switching on and off the magnon parametric oscillation by reversing the external field direction applied to a Y$_3$Fe$_5$O$_{12}$ micro-structured film. The result originates from the nonreciprocity of surface mode magnons, leading to field-direction dependence of the magnon accumulation under a nonuniform microwave pumping. Our numerical calculation well reproduces the experimental result.Comment: 5 pages, 4 figure