Non-proportionality of magnetic anisotropy and damping in CoFeB/MgO-based systems

Non-proportionality of magnetic anisotropy and damping in CoFeB/MgO-based systems
Title:
Non-proportionality of magnetic anisotropy and damping in CoFeB/MgO-based systems
Other Titles:
Applied Physics Letters
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Publication Date:
07 July 2015
Citation:
Appl. Phys. Lett. 107, 012405 (2015)
Abstract:
We study the relationship between anisotropy K and damping α in MgO/CoFeB/Ta/CoFeB/MgO/cap films using vector network analyzer ferromagnetic resonance. Capping the stack with Ta and changing the thickness of the top MgO layer allow us to create significant variations in anisotropy while keeping the thickness and process conditions of the magnetic layer constant. The change in anisotropy can be attributed to the degradation of the CoFeB/MgO interface due to Ta intermixing with MgO upon deposition. This hypothesis is supported by measurements of similar samples with the bottom MgO thickness varied instead, which exhibit no significant change in anisotropy. This method of varying K allows identifying a regime where a spin reorientation transition occurs while α remains constant, proving the non-proportionality of K and α in perpendicular CoFeB/MgO systems. The effects of changing the capping layer material, notably Ru, are also discussed.
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Description:
Copyright (2015) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Appl. Phys. Lett. 107, 012405 (2015) and may be found at http://dx.doi.org/10.1063/1.4926487.
ISSN:
0003-6951
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