Spinwave Linewidth Measurements with Low-Power RF Sources (Correspondence)

This correspondence describes a perturbation technique for obtaining the spinwave linewidth of polycrystalline garnet spheres with large values of ΔH_k. Conventions waveguide cavity techniques require power levels in the kilowatt region to excite the parallel-pump instability. By using a dielectric resonator, large RF magnetic field intensities can be generated using relatively low-power levels, and the presently available low-loss dielectric materials enable high Q-values to be attained in the resonator. Since the sensitivity of cavity perturbation techniques depend on high Q-values, the ferrite sphere can be made small enough so that perturbation assumptions apply. Results are presented for some representative polycrystalline samples. The largest spinwave linewidth measurement required a RF magnetic field intensity of approximately 27.0 Oe.