Author:
Iwata-Harms Jodi M.,Jan Guenole,Serrano-Guisan Santiago,Thomas Luc,Liu Huanlong,Zhu Jian,Lee Yuan-Jen,Le Son,Tong Ru-Ying,Patel Sahil,Sundar Vignesh,Shen Dongna,Yang Yi,He Renren,Haq Jesmin,Teng Zhongjian,Lam Vinh,Liu Paul,Wang Yu-Jen,Zhong Tom,Fukuzawa Hideaki,Wang Po-Kang
Abstract
AbstractPerpendicular magnetic anisotropy (PMA) ferromagnetic CoFeB with dual MgO interfaces is an attractive material system for realizing magnetic memory applications that require highly efficient, high speed current-induced magnetic switching. Using this structure, a sub-nanometer CoFeB layer has the potential to simultaneously exhibit efficient, high speed switching in accordance with the conservation of spin angular momentum, and high thermal stability owing to the enhanced interfacial PMA that arises from the two CoFeB-MgO interfaces. However, the difficulty in attaining PMA in ultrathin CoFeB layers has imposed the use of thicker CoFeB layers which are incompatible with high speed requirements. In this work, we succeeded in depositing a functional CoFeB layer as thin as five monolayers between two MgO interfaces using magnetron sputtering. Remarkably, the insertion of Mg within the CoFeB gave rise to an ultrathin CoFeB layer with large anisotropy, high saturation magnetization, and good annealing stability to temperatures upwards of 400 °C. When combined with a low resistance-area product MgO tunnel barrier, ultrathin CoFeB magnetic tunnel junctions (MTJs) demonstrate switching voltages below 500 mV at speeds as fast as 1 ns in 30 nm devices, thus opening a new realm of high speed and highly efficient nonvolatile memory applications.
Publisher
Springer Science and Business Media LLC
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