Improvement of Write Efficiency in Voltage-Controlled Spintronic Memory by development of a Ta- B Spin Hall Electrode

Y. Kato, Y. Saito, H. Yoda, T. Inokuchi, S. Shirotori, N. Shimomura, S. Oikawa, A. Tiwari, M. Ishikawa, M. Shimizu, B. Altansargai, H. Sugiyama, K. Koi, Y. Ohsawa, A. Kurobe

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29 Citations (Scopus)


Improving the write efficiency of magnetic tunnel junctions (MTJs) by using spin-orbit torque (SOT) is essential for realizing high-density spintronic memory. Here, we investigate a voltage-controlled spintronic memory (VoCSM) with a Ta-B spin Hall electrode. The magnetic properties of MTJs with a storage layer such as Fe-B or Co-Fe-B on an amorphous boride spin Hall electrode are found to exhibit an extremely small magnetic dead layer, a small saturation magnetization, and a large magnetic anisotropy. The spin Hall angle estimated by spin Hall magnetoresistance is -0.18 for the amorphous Ta-B spin Hall electrode, which is a magnitude twice that for a Ta spin Hall electrode. The write current density using SOT from the Ta-B spin Hall electrode is small compared with that from the β-Ta spin Hall electrode. By combining the self-aligned fabrication technique with the Ta-B electrode, a small value of critical switching current (Ic≈79μA) is achieved despite a large MTJ size (60×150nm2). We successfully reduce the write current to 48 μA, utilizing a voltage-controlled magnetic anisotropy by applying the voltage to a MTJ: VMTJ=-1V. Moreover, the device also exhibits a low write error rate (<1×10-8), high endurance (>1×1012 cycles), and large break-down voltage (>2.5V). These results indicate that VoCSM with the Ta-B spin Hall electrode could open a path to realizing high-density nonvolatile memories with low power consumption and high-speed read and write operations.

Original languageEnglish
Article number044011
JournalPhysical Review Applied
Issue number4
Publication statusPublished - 3 Oct 2018
Externally publishedYes


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