Tailoring the magnetic anisotropy of CoFeB/MgO stacks onto W with a Ta buffer layer

The emergence of perpendicular magnetic anisotropy (PMA) in CoFeB/MgO stacks deposited on W using a Ta buffer layer is studied as a function of Ta and CoFeB layer thickness and annealing temperature. It is shown that very thin Ta “dusting” layers (thickness between 0.3 and 1 nm) enhance PMA of CoFeB...

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Bibliographic Details
Published in:Applied physics letters 2015-06, Vol.106 (26)
Main Authors: Kaidatzis, Andreas, Bran, Cristina, Psycharis, Vasilios, Vázquez, Manuel, García-Martín, José Miguel, Niarchos, Dimitrios
Format: Article
Language:English
Subjects:
Anisotropy
Annealing
Applied physics
Buffer layers
Magnesium oxide
Magnetic anisotropy
Power consumption
Stacks
Thickness
Thin films
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Summary:The emergence of perpendicular magnetic anisotropy (PMA) in CoFeB/MgO stacks deposited on W using a Ta buffer layer is studied as a function of Ta and CoFeB layer thickness and annealing temperature. It is shown that very thin Ta “dusting” layers (thickness between 0.3 and 1 nm) enhance PMA of CoFeB layers grown on top of W. We find that Ta thickness is a crucial factor affecting magnetic anisotropy and it needs to be scaled proportionally to CoFeB thickness for obtaining PMA. Stacks without Ta have in-plane anisotropy, verifying the “PMA-enhancing” role of Ta. The maximum effective PMA energy (3.6×106 erg/cm3) is obtained for a stack with 1.4 nm of CoFeB and 1 nm of Ta and after annealing at 350 °C. Besides, PMA can be obtained even at the as-deposited state for certain thicknesses. This W-based CoFeB/MgO system could enable the development of low power consumption, high density, and non-volatile magnetic memories.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4923272