Resonant frequency multiplication in microscopic magnetic dots

We demonstrate the phenomenon of nonlinear frequency multiplication in sub-micrometer Permalloy dots. The efficiency of multiplication is strongly enhanced when the harmonic is resonant with the normal dynamical modes of the dot. We find that the characteristics of resonant enhancement are dependent on the spatial symmetry of the dynamical mode and are different for the double-and the triple-frequency harmonics. The resonant frequency tripling is particularly efficient, providing a practical route for the implementation of microscopic integrated microwave frequency multipliers. (C) 2011 American Institute of Physics. [doi:10.1063/1.3609011]