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Perpendicular magnetic tunnel junctions with multi-interface free layer



Pravin Khanal, Bowei Zhou, Magda Andrade, Yanliu Dang, Albert Davydov, Ali Habiboglu, Jonah Saidian, Adam Laurie, Jian-Ping Wang, Daniel Gopman, Weigang Wang


Future generations of magnetic random access memory demand magnetic tunnel junctions that can provide simultaneously high magnetoresistance, strong retention, low switching energy and small cell size below 10nm. Here we study perpendicular magnetic tunnel junctions with composite free layers where multiple ferromagnet/nonmagnet interfaces can contribute to the thermal stability. Different nonmagnetic materials (MgO, Ta, Mo) have been employed as the coupling layers in these multi-interface free layers. The dynamic change of junction properties under different annealing conditions is investigated, including tunneling magnetoresistance, magnetic anisotropy energy and interlayer exchange coupling strength. A strong dependence of tunneling magnetoresistance on the thickness of the first CoFeB layer has been observed. In junctions where Mo and MgO are used as coupling layers, large tunneling magnetoresistance above 200% has been achieved after 400°C annealing.
Applied Physics Letters


Khanal, P. , Zhou, B. , Andrade, M. , Dang, Y. , Davydov, A. , Habiboglu, A. , Saidian, J. , Laurie, A. , Wang, J. , Gopman, D. and Wang, W. (2021), Perpendicular magnetic tunnel junctions with multi-interface free layer, Applied Physics Letters, [online],, (Accessed June 20, 2024)


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Created December 15, 2021, Updated March 6, 2023