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Showing 1–7 of 7 results
Advanced filters: Author: Shingo Tamaru Clear advanced filters

  • A 0.8-nm-thick CoFe ultrathin film was deposited on a MgO tunneling barrier by means of cryogenic temperature sputtering. The cryogenic temperature sputtering at 100 K effectively suppressed island-like initial growth of CoFe without hampering grain-to-grain epitaxy, while CoFe deposited at 300 K exhibited rough and mixed interfaces. The flat and sharp interfaces in CoFe ultrathin films deposited at 100 K resulted in improved properties such as low magnetic damping, high tunneling magnetoresistance, and clear perpendicular magnetic anisotropy. Furthermore, the clear interfaces were maintained even after annealing at 673 K, indicating high thermal stability.

    • Tomohiro Ichinose
    • Tatsuya Yamamoto
    • Shinji Yuasa
    ResearchOpen Access
    NPG Asia Materials
    Volume: 17, P: 1-8

  • In a Mn3Sn/W epitaxial bilayer, spin–orbit torque induces the coherent rotation of spins, which can couple to microwave currents. Unlike in ferromagnets, the resulting conversion of AC current to DC voltage remains robust at higher frequencies, which may facilitate the development of high-speed electronic devices.

    • Shoya Sakamoto
    • Takuya Nomoto
    • Shinji Miwa
    Research
    Nature Nanotechnology
    Volume: 20, P: 216-221

  • This study clarified a large dielectric constant of MgO tunnel barriers in epitaxial magnetic tunnel junction (MTJ). The MgO tunnel barrier is subjected to compressive strain because of restraint from the underlying layers. We demonstrated that the dielectric constant of the MgO tunnel barrier and voltage controlled magnetic anisotropy (VCMA) coefficient of the epitaxial MTJ enhanced with increasing the compressive strain. Such strain engineering in epitaxial stacks makes simple rocksalt tunnel barriers more attractive for spintronics applications.

    • Tomohiro Nozaki
    • Hiroshige Onoda
    • Shinji Yuasa
    ResearchOpen Access
    NPG Asia Materials
    Volume: 17, P: 1-10

  • Highly efficient voltage control of magnetic anisotropy has been demonstrated utlizing an ultrathin Ir-doped Fe layer in MgO-based magnetic tunnel junctions. Ir adoms are dispersed inside the ultrathin Fe layer through the interdiffusion process. Large spin–orbit interaction of Ir atoms having proximity-induced magnetism is attributed to the enhancement of the voltage-controlled magnetic anisotropy (VCMA) effect. High speed response of the VCMA effect was also confirmed by voltage-induced ferromagnetic resonance. The achieved properties first satisfy the required specification for the new type of magnetoresistive random access memory (MRAM) driven by voltage.

    • Takayuki Nozaki
    • Anna Kozioł-Rachwał
    • Shinji Yuasa
    ResearchOpen Access
    NPG Asia Materials
    Volume: 9, P: e451