Role of Ta-spacer layer on tuning the tilt angle magnetic anisotropy of L11-CoPt/Ta/NiFe exchange springs

Autor: A. Talapatra, P. Saravanan, Jyoti Ranjan Mohanty, Jen-Hwa Hsu, S.V. Kamat
Rok vydání: 2017
Předmět:
Zdroj: Journal of Magnetism and Magnetic Materials. 432:82-89
ISSN: 0304-8853
DOI: 10.1016/j.jmmm.2017.01.072
Popis: L 1 1 -CoPt/Ta/NiFe trilayers are chosen as model films for probing the role of spacer layer on tuning the tilt angle magnetization ( θ M ) in such exchange springs. For this purpose, a non-magnetic layer (Ta) with varying thickness ( t Ta ) from 0 to 2.5 nm was inserted between 10-nm thick CoPt film exhibiting strong perpendicular magnetic anisotropy (PMA) and 4-nm thick NiFe film having in-plane magnetic anisotropy (IMA). With the insertion of Ta-spacer, the magnetic hysteresis loops become more and more tilted as t Ta increases. Upon increasing the t Ta from 0 to 2.5 nm, the estimated SQR ⊥ (= M r ⊥ / M s ⊥ ) from the M–H loops is found to decrease moderately; while the θ M increases significantly from 43° to 77°. MFM images revealed maze-like domain patterns and the domain size tends to increase at the expense of magnetic phase contrast with increasing t Ta . Micro-magnetic simulation of tilt in the anisotropy axis with respect to the bare CoPt-layer showed a trend similar to that of those observed with the M–H loops obtained by VSM measurements. The results of present study suggest that the insertion of Ta-spacer is not only beneficial in terms of preserving the competing anisotropies such as PMA and IMA of CoPt and NiFe-layers respectively through weakened exchange coupling; but also, act as an appropriate means for realizing tunable tilted magnetic anisotropy in the L 1 1 -CoPt/NiFe exchange springs.
Databáze: OpenAIRE
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