http://www.cnr.it/ontology/cnr/individuo/prodotto/ID32767

Modeling and characterization of irreversible switching and viscosity phenomena in perpendicular exchange-spring Fe-FePt bilayers (Articolo in rivista)

Type

Articolo in rivista (Classe)
Prodotto della ricerca (Classe)

Label

Modeling and characterization of irreversible switching and viscosity phenomena in perpendicular exchange-spring Fe-FePt bilayers (Articolo in rivista) (literal)

Anno

2008-01-01T00:00:00+01:00 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

10.1103/PhysRevB.78.184434 (literal)

Alternative label

Pellicelli R. ab; Pernechele C. ab; Solzi M. ab; Ghidini M. ab; Casoli F. c; Albertini F. c (2008)
Modeling and characterization of irreversible switching and viscosity phenomena in perpendicular exchange-spring Fe-FePt bilayers
in Physical review. B, Condensed matter and materials physics; American Physical Society (APS), College Pk (Stati Uniti d'America)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

Pellicelli R. ab; Pernechele C. ab; Solzi M. ab; Ghidini M. ab; Casoli F. c; Albertini F. c (literal)

Pagina inizio

184434-1 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url

http://prb.aps.org/abstract/PRB/v78/i18/e184434 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

78 (literal)

Rivista

Physical review. B, Condensed matter and materials physics (Rivista)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#note

In: Physical Review B, vol. 78 article n. 184434. The American Physical Society, 2008. (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali

10 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo

18 (literal)

Note

Scopu (literal)
ISI Web of Science (WOS) (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

a Univ Parma, Dipartimento Fis, I-43100 Parma, Italy; b Univ Parma, CNISM, I-43100 Parma, Italy; c Ist IMEM CNR, I-43010 Parma, Italy (literal)

Titolo

Modeling and characterization of irreversible switching and viscosity phenomena in perpendicular exchange-spring Fe-FePt bilayers (literal)

Abstract

A numerical model has been developed for simulating magnetic domain configurations, remanence, and viscosity curves in systems with strong perpendicular anisotropy and strong disorder, starting from internal switching field distributions for pinning and nucleation processes in the slow dynamics regime. In the considered systems, the domains expand in a percolationlike manner and domain configuration displays fractal properties. The simulations show that even in the case of pinning not governed by nucleation an abrupt avalanche propagation of reversed domains occurs. It is moreover evidenced that a decrease of viscosity coefficients can coexist with lowered energy barrier heights. The model has been applied to perpendicular FePt thin films with granular morphology and corresponding exchange-coupled Fe/FePt bilayers, by exploiting magnetic force microscopy, dc demagnetization DCD , isothermal remanence, and viscosity data. The comparison between magnetic viscosity phenomena in thin films and exchange-coupled bilayers has been achieved by the definition of an adimensional viscosity coefficient. The addition of the Fe layer causes a decrease of the maximum viscosity coefficient, thus demonstrating that viscosity measures can be utilized to verify the coupling of hard/soft layers. From experiments it is inferred that our samples are mainly influenced by the pinning energy barrier law, the linearity of which allows reconstructing universal viscosity curves starting from DCD data. The calculated activation volumes are comparable to the average grain volume of the FePt layer. The obtained results also demonstrate that the addition of the Fe layer leads to a widening and a shift to lower fields of the pinning field distribution, determining a decrease of both the maximum viscosity and the pinning energy barrier heights and an increase of the demagnetizing effective field. (literal)

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