Uncompensated antiferromagnetic moments in Mn-Ir/FM (FM Ni-Co, Co-Fe, Fe-Ni) bilayers: Compositional dependence and its origin

Hirokazu Takahashi, Yohei Kota, Masakiyo Tsunoda, Tetsuya Nakamura, Kenji Kodama, Akimasa Sakuma, Migaku Takahashi

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19 Citations (Scopus)

Abstract

Ferromagnetic (FM) material dependence of the uncompensated (UC) antiferromagnetic (AF) moments in AF/FM exchange biased bilayers has been studied using the x-ray magnetic circular dichroism technique in the AF/FM (AF -Mn-Ir, FM Ni-Co, Co-Fe, Fe-Ni) bilayers. The direction and magnitude of the UC-Mn moment change significantly when the composition of the FM layer changes. The crystal structure of the FM layer affects the magnitude of the UC-Mn moments. The UC-Mn moments and the FM moments of Fe-rich alloys prefer the anti-parallel alignment. Conversely, the UC-Mn moments align parallel to the FM moments in Co-rich or Ni-rich regions. A first-principles calculation pertaining to the L1 2-Mn 3Ir/FM (FM Ni 4-nCo n, Co 4-nFe n, Fe 4-nNi n; n 0, 1, 2, 3) bilayer system was carried out to characterize the UC-Mn moments near the interface. It was found that the UC-Mn moments originate from the reorientation of the magnetic moments of Mn and other ferromagnetic atoms near the AF/FM interface. The calculated result for the compositional dependence of the UC-Mn moment is in good agreement with the obtained experimental data. As a result, the dependence of the UC-Mn moment on the composition of the FM layer can be explained qualitatively based on the model that the band filling fraction modifies the direction and the magnitude of exchange coupling between AF and FM atoms, depending on the crystal structure and the composition of the FM layer.

Original languageEnglish
Article number123920
JournalJournal of Applied Physics
Volume110
Issue number12
DOIs
Publication statusPublished - 2011 Dec 15

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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