Yazar "Yu, Guoqiang" seçeneğine göre listele

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  • [ X ]
    Öğe
    Current-driven magnetization switching under zero field in Pt/Ta(wedge)/CoFeB/MgO multilayers
    (Aip Publishing, 2022) Akyol, Mustafa; Yu, Guoqiang; Wong, Kin; Wang, Kang L.
    The switching of perpendicularly magnetized ferromagnets via current-induced spin-orbit torques is of great interest because of its potential applications in memory and logic devices. However, the in-plane electric current itself is not enough to switch the magnetization. In addition to the electric current, an in-plane external magnetic field is required for magnetization switching. This limits the usage of such devices in spintronic applications. Here, we work on the current-driven perpendicular magnetization switching in the Pt/Ta(wedge)/CoFeB/MgO multilayer. The structural symmetry is broken in both z-axis and in-plane due to the wedge Ta layer, which results in a field-like spin-orbit torque. The beta( z )value extracted from the slope of the offset field vs current density increases with Ta layer thickness (< 1.0 nm) and then decreases up to z-axis asymmetries that enable the current-driven magnetization switching without the need for a magnetic field. We showed switching of the magnetization with a perpendicular magnetic anisotropy, switching in a wide range of Ta layer in Pt/Ta(wedge)/CoFeB/MgO multilayer. Published under an exclusive license by AIP Publishing.
  • [ X ]
    Öğe
    Effect of heavy metal layer thickness on spin-orbit torque and current-induced switching in Hf¦CoFeB¦MgO structures
    (Amer Inst Physics, 2016) Akyol, Mustafa; Jiang, Wanjun; Yu, Guoqiang; Fan, Yabin; Gunes, Mustafa; Ekicibil, Ahmet; Amiri, Pedram Khalili
    We study the heavy metal layer thickness dependence of the current-induced spin-orbit torque (SOT) in perpendicularly magnetized Hf broken vertical bar CoFeB broken vertical bar MgO multilayer structures. The damping-like (DL) current-induced SOT is determined by vector anomalous Hall effect measurements. A non-monotonic behavior in the DL-SOT is found as a function of the thickness of the heavy-metal layer. The sign of the DL-SOT changes with increasing the thickness of the Hf layer in the trilayer structure. As a result, in the current-driven magnetization switching, the preferred direction of switching for a given current direction changes when the Hf thickness is increased above similar to 7 nm. Although there might be a couple of reasons for this unexpected behavior in DL-SOT, such as the roughness in the interfaces and/or impurity based electric potential in the heavy metal, one can deduce a roughness dependence sign reversal in DL-SOT in our trilayer structure. Published by AIP Publishing.