Perpendicular magnetic anisotropy induced by a cap layer in ultrathin MgO/CoFeB/Nb

Perpendicular magnetic anisotropy has been observed in MgO/CoFeB/Ta but not in MgO/CoFeB/Ru, indicating that the metal cap layer is crucial. In this study, we grew MgO/CoFeB (1.2 nm)/Nb (1–2.5 nm) by sputtering and found that the magnetic anisotropy depends upon the Na thickness. The easy axis is in...

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Veröffentlicht in:Journal of applied physics 2012-08, Vol.112 (3)
Hauptverfasser: Cheng, Tsung-I, Cheng, Chih-Wei, Chern, G.
Format: Artikel
Sprache:eng
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Zusammenfassung:Perpendicular magnetic anisotropy has been observed in MgO/CoFeB/Ta but not in MgO/CoFeB/Ru, indicating that the metal cap layer is crucial. In this study, we grew MgO/CoFeB (1.2 nm)/Nb (1–2.5 nm) by sputtering and found that the magnetic anisotropy depends upon the Na thickness. The easy axis is in-plane when x = 1 nm but changes to perpendicular when x ≥ 1.2, and a transition from in-plane to perpendicular is observed at x = 1.1 nm. Perpendicular magnetic anisotropy gradually decays as the x increases, showing that it only exists in a small window of the cap Nb layer within ∼2 nm.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4742195