Brillouin Light Scattering Study of the Spin Dynamics in Nanoscale Permalloy Stripes: Theory and Experiment

The spin-wavemodesinnanoscalepermalloystripesarestudiedusingBrillouinlightscatteringforthe case whereanexternalmagneticfieldisappliedtransverselytothelengthofthestripes.Byadjusting the magnitudeofthisexternalfield,theoverallmagnetizationmaybevariedbetweenthe approximatelytransverseandlongitudinalorientations.Theobservedspin-wavefrequenciesare analysed usingarecentlydevelopedmicroscopicdipole-exchangetheorythatisparticularly appropriate whenthemagnetizationdisplaysstrongspatialinhomogeneity.Comparisonbetween theoryandexperimentforthetwosizesofstripesstudiedgivesfairlygoodagreement,allowingthe magneticparametersofpermalloytobededuced.Asmallmagneticanisotropyoftheeasy-planetypeis shown toplayanimportantrole.