Non-proportionality of magnetic anisotropy and damping in CoFeB/MgO-based systems
- Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, Singapore 117608 (Singapore)
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.
- OSTI ID:
- 22483151
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 1 Vol. 107; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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