Origin of Interfacial Magnetic Anisotropy in Ta/CoFeB/MgO and Pt/CoFeB/MgO Multilayer Thin Film Stacks

Journal Article · Fri Mar 15 00:00:00 EDT 2019 · Journal of Superconductivity and Novel Magnetism

DOI:https://doi.org/10.1007/S10948-019-5005-8· OSTI ID:22919550

Akyol, Mustafa ^[1]

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1. Adana Science and Technology University, Department of Materials Engineering (Turkey)

Interfacial perpendicular magnetic anisotropy (PMA) in Pt/Co{sub 40}Fe{sub 40}B{sub 20}/MgO and Ta/Co{sub 40}Fe{sub 40}B{sub 20}/MgO multilayer structures has been researched at various CoFeB layer thicknesses. Magneto-optical Kerr effect (MOKE) and vibrating sample magnetometer (VSM) measurements show that while strong PMA is achieved in Ta/Co{sub 40}Fe{sub 40}B{sub 20}/MgO structure for the thickness of Co{sub 40}Fe{sub 40}B{sub 20} range from 0.5 to 1.0 nm, a very weak PMA is observed in Pt/Co{sub 40}Fe{sub 40}B{sub 20}/MgO film stack for the same Co{sub 40}Fe{sub 40}B{sub 20} thicknesses. Based on the experimental results, the interfacial anisotropy energy in Ta/Co{sub 40}Fe{sub 40}B{sub 20}/MgO (1.17 erg/cm{sup 2}) was found to be almost 2.5× larger than that in Pt/Co{sub 40}Fe{sub 40}B{sub 20}/MgO (0.43 erg/cm{sup 2}). It is accepted that the PMA comes from the seed/ferromagnetic and ferromagnetic/oxide layer interfaces. Thus, the origin of interfacial magnetic anisotropy can be hybridization and/or crystallinity properties at the interfaces in Ta- and Pt-seeded stacks. While the PMA is strong in Pt/Co/MgO structure, it becomes in-plane in Fe-rich Pt/CoFeB/MgO structure. It is deduced that hybridization between 3d-5d (Co-Pt) orbitals is more dominant in Pt/CoFeB interface than 2p-3d (O-Fe) hybridization at CoFeB/MgO interface in Pt-seeded stacks. In addition, the crystallinity was studied by performing high-resolution x-ray diffraction (HR-XRD) technique. The crystal orientations of Ta and Pt are found as (002) and (111), respectively. The ferromagnetic layer might be induced out-of-plane orientation in Ta-seeded stack due to observing highly crystallized MgO (001). Thus, another reason for in-plane magnetic anisotropy in Pt/Co{sub 40}Fe{sub 40}B{sub 20}/MgO might be the absence of MgO crystallization because Pt is crystallized fcc (111) orientation.

• OSTI ID: 22919550
• Journal Information: Journal of Superconductivity and Novel Magnetism, Vol. 32, Issue 3; Other Information: Copyright (c) 2019 Springer Science+Business Media, LLC, part of Springer Nature; http://www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA); ISSN 1557-1939
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
BROMINE COMPOUNDS
COBALT COMPOUNDS
CRYSTALLIZATION
CRYSTALS
FCC LATTICES
INTERFACES
IRON COMPOUNDS
KERR EFFECT
LAYERS
MAGNESIUM OXIDES
PLATINUM
TANTALUM
TERNARY ALLOY SYSTEMS
THICKNESS
THIN FILMS
VIBRATING SAMPLE MAGNETOMETERS
X-RAY DIFFRACTION