Magnetic structures at the ferromagnetic NiFe and antiferromagnetic NiMn interface in exchange-biased films: Role of noncollinear magnetism and roughness

Kohji Nakamura, Arthur J Freeman, Ding Sheng Wang, Lieping Zhong, Juan Fernandez-De-Castro

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Abstract

The magnetic structures at the compensated ferromagnetic/antiferromagnetic (FM/AFM) interface of exchange bias FM NiFe/AFM NiMn films were determined with first-principles full-potential linearized augmented plane-wave calculations including noncollinear magnetism. The results predict that the magnetic moments of the FM NiFe layer lie perpendicular to those of the AFM NiMn layer. The intra-atomic noncollinear magnetism that arises near the interface is found to play an important role in stabilizing the perpendicular coupling that leads to a large biquadratic exchange energy (BEE). The BEE is large enough to require formation of a magnetic domain wall (with an estimated thickness ∼ 370 Å) in the AFM NiMn layers, which may account for the observed large coercivity and exchange bias. We also discuss magnetic structures at a rough FM/AFM interface-as simulated in model calculations with the inclusion of line step defects-which may contribute to a unidirectional magnetic anisotropy.

Original languageEnglish
Article number012402
Pages (from-to)124021-124024
Number of pages4
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume65
Issue number1
Publication statusPublished - Jan 1 2002

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ASJC Scopus subject areas

  • Condensed Matter Physics

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