Domain imaging, MOKE and magnetoresistance studies of CoFeB films for MRAM applications

• Type: Article in International Scientific Journal
• Date: 2006

Authors

Teixeira, José Miguel (Author) FCUP; Silva, Rui F A (Author) Other; Ventura, João Oliveira Oliveira (Author) Other; Pereira, André M. (Author) FCUP; Carpinteiro, F. C. (Author) Other; Araújo, João Pedro (Author) FCUP; Sousa, João Bessa (Author) FCUP; Cardoso, Susana (Author) Other; Ferreira, Ricardo A. (Author) Other; Freitas, P. P. P Peixeiro (Author) Other

Journal

Title: Materials Science & Engineering B: Solid-State Materials for Advanced Technology

Vol. 126

Pages: 180-186

ISSN: 0921-5107

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 29 Citations

Scopus - 32 Citations

Other information

Authenticus ID: P-004-NNB

DOI: 10.1016/j.mseb.2005.09.031

Abstract (EN): We present a detailed study on domain imaging, Kerr effect magnetometry (MOKE) and magnetoresistance (MR), for a series of 20 nm Co73.8Fe16.2B10 thin films, both as-deposited (amorphous) and annealed (crystalline). By considering the two different (orthogonal) in-plane magnetization components, obtained by MOKE measurements, we were able to study the uniaxial anisotropy induced during CoFeB-deposition and to discriminate the magnetization processes under a magnetic field parallel and perpendicular to such axis. MOKE magnetic imaging enabled us to observe the dominant magnetization processes, namely domain wall motion and moment rotation. These processes were correlated with the behavior of the magnetoresistance, which depends both on short-range spin disorder electron scattering and on the angle between the electrical current and the spontaneous magnetization (M-S). A simple numerical treatment based on Stoner-Wolfarth model enables us to satisfactorily predict the magnetization behaviour observed in these films. A comparison between the results in Co73.8Fe16.2B10 films and the previous ones obtained in annealed Co80Fe20 films, show that the introduction of boron in CoFe reduces significantly the coercive and saturation fields along the easy axis (e.g. H-c from similar to 2 kA m(-1) down to similar to 0.5 kA m(-1)). Also, the magnetization along the hard axis saturates at lower fields. We conclude that amorphous and nanocrystalline CoFeB films show low coercive fields and abrupt switching, as well as absence of short-range spin disorder effects after switching when compared with Co80Fe20.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7