Subsidiary Resonance in YIG

The real and imaginary components of susceptibility at subsidiary resonance have been measured for a polished YIG sphere at 9253 Mc. These measurements were made as a function of dc magnetic field and power level for $h_{\mathrm{rf}}$ , both parallel and perpendicular to the applied magnetic field, with a cw and a pulsed pumping source. The initial increase in χ′′ with power level for a cw source is found to be much more gradual than theory would predict for the perpendicular case. Furthermore, intense relaxation oscillations are observed at high power levels for both parallel and perpendicular pumping. The real part of the susceptibility, χ′, shows a small increase for the parallel pumped case; for the perpendicular pumped case χ′ first decreases and then increases with respect to its low power value as $H_{\mathrm{dc}}$ traverses the subsidiary resonance.