A Simple Method for Determining Magnetostatic Mode Frequency and Pattern

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Abstract
To survey all the magnetostatic modes in a sample of any form, modes are regarded as superpositions of spin waves. A rough estimation of mode pattern and frequency is obtained from the azimuthal (m), radial (r), and longitudinal (l=n-m-2r) indices with n, m, r after the notation of Fletcher and Bell. The well-known guided-wave solutions in thin disks and in long rods are briefly reviewed by the superposition idea and are combined to get the resonances of cylinders. These are determined by longitudinal as well as transversal boundary conditions, which may originate from internal cutoff conditions rather than from the reflecting sample surface. As an example, the resonances in normally magnetized thin disks are treated more extensively, and are investigated experimentally, in seven different resonator sites, at the frequency of 6525 MHz. The measured resonances have been identified in (m+2r)-groups by symmetry considerations which follow from the mode indices. The resonance fields have been checked theoretically within about 20 G. Intensity and broadness of various resonances indicate a strong coupling to the whole resonator mode with a partial breakdown of local fields. The main resonance is damped selectively by higher-order modes.