Probing vertically graded anisotropy in FePtCu films
Dumas, Randy K. (University of Gothenburg. Department of Physic)
Fang, Yeyu (Kungl. Tekniska högskolann. Materialfysik)
Kirby, Brian (Brian J.) (NIST Center for Neutron Research)
Zha, Chaolin (Kungl. Tekniska högskolann. Materialfysik)
Bonanni, Valentina (Kungl. Tekniska högskolann. Materialfysik)
Nogués, Josep (Institut Català de Nanociència i Nanotecnologia)
Aakerman, Johan (Kungl. Tekniska högskolann. Materialfysik)

Date:	2011
Abstract:	Field-dependent polarized neutron reflectivity (PNR) and magnetometry are employed to study the magnetic properties of compositionally uniform and graded FePtCu films as a function of annealing temperature (TA). The PNR results are able to directly probe the compositional and anisotropy variations through the film thickness. Further details about how the reversal mechanisms evolve are then elucidated by using a first-order reversal curve technique. The reversal of the graded sample annealed at 300º C occurs by an initial rapid switching of the dominant soft A1 phase toward the surface of the film, followed by the gradual reversal of the residual hard phase components toward the bottom. This indicates that the anisotropy gradient is not well established at this low TA. A fundamentally different mechanism is found after annealing at 400ºC, where the rapid switching of the entire film is preceded by a gradual reversal of the soft layers. This suggests that the anisotropy gradient has become better established through the film thickness. The field-dependent PNR measurements confirm the existence of an anisotropy gradient, where the lower (higher) anisotropy portions are now toward the bottom (top) of the film because of the Cu compositional gradient. However, after annealing at 500º C,a single rapid reversal is found, indicating the formation of a uniform hard film. In this case, PNR demonstrates a more uniform magnetic depth profile that is consistent with a uniform reference sample, suggesting significant interdiffusion of the Cu is degrading the compositional and induced anisotropy gradient at this elevated TA.
Grants:	Agència de Gestió d'Ajuts Universitaris i de Recerca 2009/SGR-1292 Ministerio de Ciencia e Innovación MAT2010-20616-C02-02
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; Versió publicada
Subject:	Matèria ; Propietats
Published in:	Physical review B : condensed matter and materials physics, Vol. 84, N. 5 (Aug. 2011) , p. 054434/1-054434/9, ISSN 1098-0121

DOI: 10.1103/PhysRevB.84.054434

9 p, 2.3 MB

The record appears in these collections:
Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Group of Smart Nanoengineered Materials, Nanomechanics and Nanomagnetism (Gnm3)
Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Published articles