We present in-plane CoFeB-MgO magnetic tunnel junctions with perpendicular magnetic anisotropy in the free layer to reduce the spin transfer induced switching current. The tunneling magnetoresistance ratio, resistance-area product, and switching current densities are compared in magnetic tunnel junctions with different CoFeB compositions. The effects of CoFeB free layer thickness on its magnetic anisotropy and current-induced switching characteristics are studied by vibrating sample magnetometry and electrical transport measurements on patterned elliptical nanopillar devices. Switching current densities ∼4 MA/ cm2 are obtained at 10 ns write times.
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The authors would like to thank T. Rahman, J. G. Alzate, P. Upadhyaya, M. Lewis, and J. Wrona. This work was supported by the DARPA STT-RAM (HR0011-09-C-0114) program, and by the Nanoelectronics Research Initiative through the Western Institute of Nanoelectronics.