Enhanced spin–orbit torque <b>
                     <i>via</i>
                  </b> interface engineering in Pt/CoFeB/MgO heterostructures

Lee, Hae Yeon; Kim, Sang-Hoon; Park, June Young; Oh, Young Wan; Park, Seung Young; Ham, Wooseung; Kotani, Yoshinori; Nakamura, Tetsuya; Suzuki, Motohiro; Ono, Teruo; Lee, Kyung Jin; Park, Byong‐Guk

doi:10.1063/1.5084201

Cited by 59 publications

(25 citation statements)

References 59 publications

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“…However, T int cannot account for the different signs of the θ eff SH (or ξ DLT ) between the Co/Cr and Ni/Cr samples since it can only reduce the magnitude of the ξ DLT by diminishing the transmission of spin (or orbital) currents. Second, we examine the interfacial contributions [33][34][35][36][37][38] to θ eff SH by measuring the Cr thickness (t Cr ) dependence of the ξ DLT for the FM/Cr samples. If the positive θ eff SH of the Ni/Cr samples is due to the interfacial effect, ξ DLT decreases with increasing t Cr and eventually changes its sign to negative for thicker t Cr 's where bulk Cr with negative σ Cr SH dominates.…”

Section: Resultsmentioning

confidence: 99%

Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching

et al. 2021

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Spin Hall effect, an electric generation of spin current, allows for efficient control of magnetization. Recent theory revealed that orbital Hall effect creates orbital current, which can be much larger than spin-Hall-induced spin current. However, orbital current cannot directly exert a torque on a ferromagnet, requiring a conversion process from orbital current to spin current. Here, we report two effective methods of the conversion through spin-orbit coupling engineering, which allows us to unambiguously demonstrate orbital-current-induced spin torque, or orbital Hall torque. We find that orbital Hall torque is greatly enhanced by introducing either a rare-earth ferromagnet Gd or a Pt interfacial layer with strong spin-orbit coupling in Cr/ferromagnet structures, indicating that the orbital current generated in Cr is efficiently converted into spin current in the Gd or Pt layer. Our results offer a pathway to utilize the orbital current to further enhance the magnetization switching efficiency in spin-orbit-torque-based spintronic devices.

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Section: Resultsmentioning

confidence: 99%

Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching

et al. 2021

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“… 32 , 33 Therefore, interface engineering and quantifying the REE become significant for the optimization of SOT-based devices. 34 − 36 The spin currents injected into the F layer and SOTs may be examined by electric measurements through its magnetoresistance 37 − 39 and the anomalous Hall effect (AHE). 40 The change of the resistance of the hybrid structure caused by the above effects is referred to as spin Hall magnetoresistance (SMR).…”

Section: Introductionmentioning

confidence: 99%

Study of Spin–Orbit Interactions and Interlayer Ferromagnetic Coupling in Co/Pt/Co Trilayers in a Wide Range of Heavy-Metal Thickness

Ogrodnik

Grochot

Karwacki

et al. 2021

ACS Appl. Mater. Interfaces

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The spin–orbit torque, a torque induced by a charge current flowing through the heavy-metal-conducting layer with strong spin–orbit interactions, provides an efficient way to control the magnetization direction in heavy-metal/ferromagnet nanostructures, required for applications in the emergent magnetic technologies like random access memories, high-frequency nano-oscillators, or bioinspired neuromorphic computations. We study the interface properties, magnetization dynamics, magnetostatic features, and spin–orbit interactions within the multilayer system Ti(2)/Co(1)/Pt(0–4)/Co(1)/MgO(2)/Ti(2) (thicknesses in nanometers) patterned by optical lithography on micrometer-sized bars. In the investigated devices, Pt is used as a source of the spin current and as a nonmagnetic spacer with variable thickness, which enables the magnitude of the interlayer ferromagnetic exchange coupling to be effectively tuned. We also find the Pt thickness-dependent changes in magnetic anisotropies, magnetoresistances, effective Hall angles, and, eventually, spin–orbit torque fields at interfaces. The experimental findings are supported by the relevant interface structure-related simulations, micromagnetic, macrospin, as well as the spin drift-diffusion models. Finally, the contribution of the spin–orbital Edelstein–Rashba interfacial fields is also briefly discussed in the analysis.

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“…The interfaces were further confirmed as prominent sources for generating substantial SOTs in Pt(O)/FM, W(O)/FM, NiFe/Cu(O), Pt/CoFeB/MgO/SiO 2 , and Pt/Co/TiO x structures with highly resistive or insulating oxygen-incorporated metals ( An et al., 2016 , 2018b ; Qiu et al., 2015 ; Bekele et al., 2018 ; Demasius et al., 2016 ). More specific interface modifications by using Cu, Ti, or Hf insertion layers between the HM and the FM layers were also performed ( Rojas-Sánchez et al., 2014 ; Huang et al., 2015 ; Lee et al., 2019 ; Shi et al., 2018 ; Zhu et al., 2019b ), where improved interfacial spin transparency T int and thereby enhanced θ SH,eff were obtained. Besides, the oxide/HM interface can also contribute to the overall SOTs in an oxide/HM/FM structure in terms of efficiency and direction ( Sheng et al., 2019 ; Li et al., 2020 ).…”

Section: Key Challenges For Spin-orbitronic Devicesmentioning

confidence: 99%

Prospect of Spin-Orbitronic Devices and Their Applications

et al. 2020

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Summary Science, engineering, and medicine ultimately demand fast information processing with ultra-low power consumption. The recently developed spin-orbit torque (SOT)-induced magnetization switching paradigm has been fueling opportunities for spin-orbitronic devices, i.e., enabling SOT memory and logic devices at sub-nano second and sub-picojoule regimes. Importantly, spin-orbitronic devices are intrinsic of nonvolatility, anti-radiation, unlimited endurance, excellent stability, and CMOS compatibility, toward emerging applications, e.g., processing in-memory, neuromorphic computing, probabilistic computing, and 3D magnetic random access memory. Nevertheless, the cutting-edge SOT-based devices and application remain at a premature stage owing to the lack of scalable methodology on the field-free SOT switching. Moreover, spin-orbitronics poises as an interdisciplinary field to be driven by goals of both fundamental discoveries and application innovations, to open fascinating new paths for basic research and new line of technologies. In this perspective, the specific challenges and opportunities are summarized to exert momentum on both research and eventual applications of spin-orbitronic devices.

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Enhanced spin–orbit torque via interface engineering in Pt/CoFeB/MgO heterostructures

Cited by 59 publications

References 59 publications

Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching

Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching

Study of Spin–Orbit Interactions and Interlayer Ferromagnetic Coupling in Co/Pt/Co Trilayers in a Wide Range of Heavy-Metal Thickness

Prospect of Spin-Orbitronic Devices and Their Applications

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