Observation of boron diffusion in an annealed Ta/CoFeB/MgO magnetic tunnel junction with standing-wave hard x-ray photoemission

The CoFeB/MgO system shows promise as a magnetic tunnel junction with perpendicular magnetization and low critical current densities for spin-torque driven magnetization switching. The distribution of B after annealing is believed to be critical to performance. We have studied the distribution of B...

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Bibliographic Details
Published in:Applied physics letters 2012-11, Vol.101 (20)
Main Authors: Greer, A. A., Gray, A. X., Kanai, S., Kaiser, A. M., Ueda, S., Yamashita, Y., Bordel, C., Palsson, G., Maejima, N., Yang, S.-H., Conti, G., Kobayashi, K., Ikeda, S., Matsukura, F., Ohno, H., Schneider, C. M., Kortright, J. B., Hellman, F., Fadley, C. S.
Format: Article
Language:English
Subjects:
Annealing
Diffusion
Magnesium oxide
Magnetization
Mathematical analysis
Tantalum
Tunnel junctions
X-rays
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Summary:The CoFeB/MgO system shows promise as a magnetic tunnel junction with perpendicular magnetization and low critical current densities for spin-torque driven magnetization switching. The distribution of B after annealing is believed to be critical to performance. We have studied the distribution of B in a Ta/Co0.2Fe0.6B0.2/MgO sample annealed at 300 °C for 1 h with standing-wave hard x-ray photoemission spectroscopy (SW-HXPS). Comparing experimental rocking curve data to x-ray optical calculations indicates diffusion of 19.5% of the B uniformly into the MgO and of 23.5% into a thin TaB interface layer. SW-HXPS is effective for probing depth distributions in such spintronic structures.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4766351