Characterization of Spin-Wave Eigenmodes in Normally Magnetized Nano-Pillars

Abstract

The eigen-modes of spin waves in a circular spin-valve nano-pillar that is perpendicularly magnetised along z are studied spectroscopically and reported here. Magnetic Resonance Force Microscopy (MRFM) is used to conduct spectroscopy. Depending on whether an RF current running perpendicularly through the layers or a homogeneous in-plane RF magnetic field excites the nano-pillar, different spectra are observed. These findings are consistent with micromagnetic simulations of the local magnetization's time decay response to excitations with various azimuthal symmetries, (x iy)e−i4̄. Because of the orthoradial symmetry of the induced RF Oersted field, only four 0 modes are stimulated by the RF magnetic field and only four 1 modes are excited by the RF current, indicating that the azimuthal 4-index is the discriminating parameter for the selection criteria.