Parametric excitation of surface magnetostatic modes in an axially magnetized elliptic cylinder under longitudinal pumping

TL;DR

This paper develops an analytical theory for the parametric excitation of surface magnetostatic modes in an elliptic ferrite cylinder under longitudinal pumping, revealing mode-dependent thresholds and polarization characteristics.

Contribution

It provides the first rigorous analytical model accounting for boundary conditions and mode interactions in elliptic cylinders under longitudinal pumping.

Findings

Parametric excitation of counter-propagating surface modes at half the pump frequency.

Threshold depends strongly on mode number and aspect ratio.

Derived relation between polarization ellipse ratio and excitation threshold.

Abstract

A rigorous analytical theory of parametric excitation under the longitudinal pumping has been developed for the surface magnetostatic modes of a long elliptic ferrite cylinder magnetized along its axis with regard for the boundary conditions at the surface of the cylinder.It is shown that a pair of frequency-degenerated counter-propagating surface modes at half the pumping frequency can be parametrically excited, and the expressions for the corresponding parametric excitation threshold have been derived. The threshold demonstrates a strong dependence on the mode number and elliptic cylinder's aspect ratio and tends from above for the large aspect ratio to the value deduced on the basis of the plane-wave analysis.The simple analytical relation between the ratio of axes of the high-frequency magnetization polarization ellipse of excited surface magnetostatic oscillations and the parametric excitation threshold is obtained, discussed, and graphically illustrated.