Anantharaman, M R; Hysen, T; Salim, Al-Harthi; Al-Omari, I A; Geetha, P; Lisha, R; Ramanujan, R V; Sakthi Kumar, D(Elsevier, April 18, 2013)
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Abstract:
Co–Fe–Si based films exhibit high magnetic moments and are highly sought after for applications like soft under layer sinper pendicular recording mediatomagneto-electro-mechanical sensor applications.In this workt he effect of annealing on
s tructural,morphologicaland magnetic propertiesofco–Fe–Si thin films wasinvestigated.compositional analysis using x-rayphotoelectron spectroscopy and secondary ion massspectroscopyrevealedanativeoxidesurfacelayerconsistingofoxidesofco,feandsionthe surface. The morphology of theas deposited films shows mound like structures conformingtothe Volmer–Webergrowthmodel.Nanocrystallisationofamorphous films upon annealing was observed by glancing anglex-raydiffraction and transmission electron microscopy.Theevolutionofmagnetic properties with annealing is explained using the Herzermodel.Vibrating sample magnetometry measurements carried out at various angles from01 to 901 to the applied magnetic field were employed to study the angula rvariation of coercivity.The angular variation fits the modified Kondorsky model. Interestingly,the coercivity evolution with annealing deduced frommagneto-opticalKerreffectstudies indicates areversetrendcomparedtomagetisationobservedinthebulk.Thiscanbeattributedtoa domain wallpinningatnativeoxidelayeronthesurfaceofthin films. Theevolutionofsurfacemagnetic properties iscorrelatedwithmorphologyevolutionprobedusingatomicforcemicroscopy.The morphology aswellasthepresenceofthenativeoxidelayerdictatesthesurfacemagneticproperties and this is corroborated by the apparent difference in the bulk and surface magnetic properties
Anantharaman, M R; Swapna, Nair S; Mercy, Mathews; Joy, P A; Kulkarni, S D(Elsevier, July 26, 2004)
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Abstract:
Superparamagnetic nanocomposites based on g-Fe2O3 and sulphonated polystyrene have been synthesized by ion
exchange process and the preparation conditions were optimized. Samples were subjected to cycling to study the effect
of cycling on the magnetic properties of these composites. The structural and magnetization studies have been carried
out. Magnetization studies show the dependence of magnetization on the number of ion exchange cycles. Doping of
cobalt at the range in to the g-Fe2O3 lattice was effected in situ and the doping was varied in the atomic percentage
range 1–10. The exact amount of cobalt dopant as well as the iron content was estimated by Atomic Absorption
Spectroscopy. The effect of cobalt in modifying the properties of the composites was then studied and the results
indicate that the coercivity can be tuned by the amount of cobalt in the composites. The tuning of both the
magnetization and the coercivity can be achieved by a combination of cycling of ion exchange and the incorporation of
cobalt
Description:
Journal of Magnetism and Magnetic Materials 283 (2004) 344–352