Atomic-scale electron spectroscopic imaging on sputtered magnetic tunnel junctions (MTJs) with a thin, , MgO layer and B-alloyed electrodes reveals B diffusion into the MgO, resulting in a Mg–B–O tunnel barrier. This thick interfacial layer forms due to oxidation of CoFeB during radio frequency sputtering of MgO and subsequent B diffusion into MgO during annealing. We measure a room-temperature tunneling magnetoresistance (TMR) of in IrMn/CoFeB/Mg–B–O/CoFeB MTJs after annealing, demonstrating that thin Mg–B–O barriers can produce relatively high TMR.
Atomic-scale spectroscopic imaging of CoFeB/Mg–B–O/CoFeB magnetic tunnel junctions
J. J. Cha, J. C. Read, W. F. Egelhoff, P. Y. Huang, H. W. Tseng, Y. Li, R. A. Buhrman, D. A. Muller; Atomic-scale spectroscopic imaging of CoFeB/Mg–B–O/CoFeB magnetic tunnel junctions. Appl. Phys. Lett. 20 July 2009; 95 (3): 032506. https://doi.org/10.1063/1.3184766
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