Ionization and Displacement Damage on Nanostructure of Spin–Orbit Torque Magnetic Tunnel Junction

Bi Wang,Liang Wang,Chaoming Liu,Yudong Zhuo,Min Wang,Jun Wang,Kaihua Cao,Hongchao Zhang,Youguang Zhang,Xiangyue Ma,Hongqiang Zhang,Weisheng Zhao,Tianqi Wang,Yuanfu Zhao,Zhaohao Wang

doi:10.1109/tns.2021.3134685

Abstract

Spin–orbit torque magnetic tunnel junction (SOT-MTJ) is the memory cell of magnetic random access memory (MRAM), which is a promising candidate for upper level cache in the harsh environment due to nonvolatility, high speed, and high endurance. Therefore, it is significant to research the mechanism of irradiation effects on the SOT-MTJ before its integration onboard. This article investigates the ionization and displacement damage of in-plane magnetic anisotropy SOT-MTJ, including 1-MeV electron and 17.2-keV He + and 60 Co gamma irradiations with various fluences and doses, respectively. The devices are resilient to tunnel magnetoresistance (TMR), whereas the magnetic properties are changed after irradiation. The 100-Mrad (Si) gamma and 17.2-keV He + irradiations generate similar damages on the device performances, in the aspects of the magnetic anisotropy and critical current density ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$J_{\mathrm {c}}$ </tex-math></inline-formula> ). However, the displacement damage originating from the electron irradiation does not have a significant influence on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$J_{\mathrm {c}}$ </tex-math></inline-formula> . In addition, the saturation magnetization and exchange bias field are changed by irradiations without regularity. Some possible mechanisms are discussed to explain the experimental results through the simulation of stopping and range of ions in matter (SRIM) and microstructural tests.

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