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تسجيل مستخدم جديدEnhanced spin-orbit torque via interface engineering in Pt/CoFeB/MgO heterostructures
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Spin-orbit torque facilitates efficient magnetization switching via an in-plane current in perpendicularly magnetized heavy metal/ferromagnet heterostructures. The efficiency of spin-orbit-torque-induced switching is determined by the charge-to-spin conversion arising from either bulk or interfacial spin-orbit interactions, or both. Here, we demonstrate that the spin-orbit torque and the resultant switching efficiency in Pt/CoFeB systems are significantly enhanced by an interfacial modification involving Ti insertion between the Pt and CoFeB layers. Spin pumping and X-ray magnetic circular dichroism experiments reveal that this enhancement is due to an additional interface-generated spin current of the nonmagnetic interface and/or improved spin transparency achieved by suppressing the proximity-induced moment in the Pt layer. Our results demonstrate that interface engineering affords an effective approach to improve spin-orbit torque and thereby magnetization switching efficiency.
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Spin-orbit torque manifested as an accumulated spin-polarized moment at nonmagnetic normal metal, and ferromagnet interfaces is a promising magnetization switching mechanism for spintronic devices. To fully exploit this in practice, materials with a
high spin Hall angle, i.e., a charge-to-spin conversion efficiency, are indispensable. To date, very few approaches have been made to devise new nonmagnetic metal alloys. Moreover, new materials need to be compatible with semiconductor processing. Here we introduce W-Ta and W-V alloys and deploy them at the interface between $beta$-W/CoFeB layers. First, spin Hall conductivities of W-Ta and W-V structures with various compositions are carried out by first-principles band calculations, which predict the spin Hall conductivity of the W-V alloy is improved from $-0.82 times 10^3$ S/cm that of W to $-1.98 times 10^3$ S/cm. Subsequently, heterostructure fabrication and spin-orbit torque properties are characterized experimentally. By alloying $beta$-W with V at a concentration of 20 at%, we observe a large enhancement of the absolute value of spin Hall conductivity of up to $-(2.77 pm 0.31) times 10^3$ S/cm. By employing X-ray diffraction and scanning transmission electron microscopy, we further explain the enhancement of spin-orbit torque efficiency is stemmed from W-V alloy between W and CoFeB.
Spin current generated by spin Hall effect in the heavy metal would diffuse up and down to adjacent ferromagnetic layers and exert torque on their magnetization, called spin-orbit torque. Antiferromagnetically coupled trilayers, namely the so-called
synthetic antiferromagnets (SAF), are usually employed to serve as the pinned layer of spintronic devices based on spin valves and magnetic tunnel junctions to reduce the stray field and/or increase the pinning field. Here we investigate the spin-orbit torque in MgO/CoFeB/Ta/CoFeB/MgO perpendicularly magnetized multilayer with interlayer antiferromagnetic coupling. It is found that the magnetization of two CoFeB layers can be switched between two antiparallel states simultaneously. This observation is replicated by the theoretical calculations by solving Stoner-Wohlfarth model and Landau-Lifshitz-Gilbert equation. Our findings combine spin-orbit torque and interlayer coupling, which might advance the magnetic memories with low stray field and low power consumption.
Voltage control of magnetism and spintronics have been highly desirable, but rarely realized. In this work, we show voltage-controlled spin-orbit torque (SOT) switching in W/CoFeB/MgO films with perpendicular magnetic anisotropy (PMA) with voltage ad
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We study the spin-orbit torque (SOT) effective fields in Cr/CoFeAl/MgO and Ru/CoFeAl/MgO magnetic heterostructures using the adiabatic harmonic Hall measurement. High-quality perpendicular-magnetic-anisotropy CoFeAl layers were grown on Cr and Ru lay
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