Origin of Interfacial Magnetic Anisotropy in Ta/CoFeB/MgO and Pt/CoFeB/MgO Multilayer Thin Film Stacks
[ X ]
Tarih
2019
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Springer
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Interfacial perpendicular magnetic anisotropy (PMA) in Pt/Co40Fe40B20/MgO and Ta/Co40Fe40B20/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/Co40Fe40B20/MgO structure for the thickness of Co40Fe40B20 range from 0.5 to 1.0nm, a very weak PMA is observed in Pt/Co40Fe40B20/MgO film stack for the same Co40Fe40B20 thicknesses. Based on the experimental results, the interfacial anisotropy energy in Ta/Co40Fe40B20/MgO (1.17erg/cm(2)) was found to be almost 2.5x larger than that in Pt/Co40Fe40B20/MgO (0.43erg/cm(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/Co40Fe40B20/MgO might be the absence of MgO crystallization because Pt is crystallized fcc (111) orientation.
Açıklama
Anahtar Kelimeler
PMA, Thin films, Magnetic multilayer stacks, Spintronics
Kaynak
Journal of Superconductivity and Novel Magnetism
WoS Q Değeri
Q4
Scopus Q Değeri
Q2
Cilt
32
Sayı
3
