Irreversibleevolutionofangular-dependentcoercivityinFe۸۰Ni۲۰ nanowirearrays:Detectionofasinglevortexstate

چکیده مقاله

The irreversibleevolutionofmagneticcoercivityinarraysof75nmdiameterFe80Ni20 nanowires(NWs) has beenexploredbymeansof first-order reversalcurve(FORC)analysisasafunctionoftheangle between themagnetic field andtheNWaxis(0°rθr90°). TheFe80Ni20 NWs withlengthsupto60 μm werefabricatedusingapulsedelectrodepositionmethodintohard-anodicaluminumoxidetemplates with aninterporedistanceof275nm.Investigatingtheinterwireandintrawiremagnetostaticinterac- tions, theangularFORC(AFORC)diagramsindicatedenhancedintrawireinteractionswithincreasing length and θ (o90°), inducedbyamagnetizationreversalthroughvortexdomainwall(VDW)propa- gation. Intriguingly,inadditiontotheVDWmode,asinglevortexstatewithbroadirreversibleswitching of nucleationandannihilation fields wasdetectedat θ¼83° for 60 μm longNWs.At θ¼90°, theNWs reversedmagnetizationthroughtransversedomainwall,involvingareversiblecomponentbyafraction of 95%.Furthermore,thetransitionanglebetweenthereversalmodeswasfoundtodecreasewithin- creasing aspectratiofrom200to800.Theirreversibleangular-dependentcoercivity(Hc Irrev(θ)) of Fe80Ni20 NWs wasextractedfromtheAFORCmeasurementsandcomparedwiththemajorangular dependence ofcoercivity(Hc Major(θ)) obtainedfromtheconventionalhysteresisloopmeasurements. While Hc Major(θ) showedanon-monotonicbehavior, Hc Irrev(θ) constantlyincreasedwithincreasing θ (o90°). Ontheotherhand,usinganalyticalmodels,a93%agreementwasobtainedbetweenthethe- oretical angular-dependentnucleation field andexperimental Hc Irrev(θ) forirreversibleswitchingofVDW when 0°rθr86°.