Strong Spin-Orbit Torque Induced by the Intrinsic Spin Hall Effect in 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>Cr</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Pt</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:math>

Liu, Qianbiao; Li, Jingwei; Zhu, Lujun; Lin, Xin; Xie, Xinyue; Zhu, Lihua

doi:10.1103/physrevapplied.18.054079

Cited by 10 publications

(5 citation statements)

References 60 publications

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“…This dampinglike torque efficiency provided by the 2 nm Pt 0.75 Cu 0.25 is 2–3 times smaller than that provided by 4–6 nm Pt-X alloys (X = Ti, MgO, Cr, Si 3 N 4 , etc.) with similar resistivity (typically ≥0.25). ,,− This is consistent with the prediction of the drift-diffusion analysis that provided the spin Hall effect of a certain HM would decrease toward zero as the HM thickness is reduced to well below 4 times the spin-diffusion length due to the reduction of the interfacial spin transparency by spin backflow . Meanwhile, there could be non-negligible spin memory loss that decreases T int and thus of the Pt 0.75 Cu 0.25 /Co interfaces by spin–orbit scattering as indicated by the sizable K s values of 0.88–0.96 erg/cm 2 .…”

supporting

confidence: 79%

“…The excellent linear scaling of the SOTs with the repeat number unambiguously evidences that the stacking of the superlattice simply accumulates the spin Hall torques (Figure a) and does not introduce any additional spin-current generation mechanism by the stacking itself. As revealed by previous studies ,,− and discussed in a previous review, the SOTs in the Pt-X/FM systems are predominately generated by the spin Hall effect of the Pt-X, while interfacial SOC effects have an only negligible torque contribution in magnetic bilayers and the symmetry-preserved [Pt/Co] n superlattice with strong interfacial SOC. The 1.5 nm symmetry-breaking layers should play an only minor role in the giant enhancement of the dampinglike SOT because we have measured negligible SOTs due to the 1 or 1.5 nm Ta layers in the control samples of the Ta (1 nm)/Co/MgO , and Ta (1 nm)/Co/Ta (1.5 nm) samples.…”

mentioning

confidence: 66%

“…Technological impacts of the symmetry-broken superlattices. (a) Comparison of the dampinglike SOT efficiency and resistivity of the strong SOT materials Pt-X, ,,− PtTe 2 , [Pt/Co/MgO] 10 , Pt-Hf/NiO, β-Ta, β-W, and [Pt 0.75 Cu 0.25 /Co/Ta] 16 . Proposals of (b) a self-torqued magnetic tunnel junction utilizing a superlattice bit and (c) a self-torqued superlattice racetrack for magnetic memory, logic, and microwave emitter applications.…”

mentioning

confidence: 99%

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Giant, Linearly Increasing Spin–Orbit Torque Efficiency in Symmetry-Broken Spin–Orbit Torque Superlattices

Lin,

Zhu,

Liu

et al. 2023

Nano Lett.

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Magnetic heterostructures with high spin–orbit torque efficiency and low impedance have great promise for low-power spintronic technologies. We report a symmetry-broken spin–orbit superlattice [Pt0.75Cu0.25/Co/Ta] n , in which the dampinglike spin–orbit torque efficiency accumulates linearly with the repeat number n and achieves a giant value of >200% when n = 16, which is 100 times stronger than that of a conventional magnetic heterostructure with a clean Pt (e.g., 2% at a resistivity of 7 μΩ cm). The giant spin–orbit torque effect arises predominantly from the spin Hall effect of Pt0.75Cu0.25. The anomalous Nernst effect increases remarkably as the repeat number n increases, implying a critical need to include the thermal effect in the analysis of magnetic superlattices and multilayers. The giant spin–orbit torque, low resistivity, and strong anomalous Nernst effect suggest the great potential of the superlattice [Pt0.75Cu0.25/Co/Ta] n for low-power memory and logic technologies as well as high-performance thermoelectric battery and sensor applications.

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confidence: 79%

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confidence: 66%

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confidence: 99%

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Giant, Linearly Increasing Spin–Orbit Torque Efficiency in Symmetry-Broken Spin–Orbit Torque Superlattices

Lin,

Zhu,

Liu

et al. 2023

Nano Lett.

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“…ξ is the SOT efficiency which is equal to T int θ sh [30,31], with θ sh being the spin Hall angle, and T int the spin transparency of the interface [8]. β denotes the relative strength of the fieldlike SOT to the dampinglike one, which can be chosen or tuned by various ways [4][5][6][7][8][9][10][11][12][13].…”

Section: Modelmentioning

confidence: 99%

“…For instance, it can be directly detected through magneto-optical Kerr effect [2], or evaluated by the ferromagnetic resonance technique [3,4]. Intriguingly, the fieldlike torque can be modulated by changing the thickness of the heavy-metal layer [4][5][6] or that of the ferromagnetic layer [6][7][8][9], by tuning the interfacial oxidation [10,11], by varying the concentration of heavy-metal alloy [12], and by the spin-orbit proximity effect via inserting other layers [13], as well as by controlling the interfacial spin transparency via properly annealing [8]. By these means, the fieldlike torque changes drastically and even becomes stronger than the dampinglike torque [5,11], as well as switches its sign [6,9,10].…”

Section: Introductionmentioning

confidence: 99%

Field-free self-oscillation of magnetization enabled by the fieldlike spin-orbit torque

Wang,

Wan

et al. 2023

Phys. Scr.

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Fieldlike spin-orbit torque, which behaves like a torque from a magnetic field, but relies on the current together with the damplike one, was recognized to influence magnetization switching. However, its role on magnetic oscillations remains to be explored. By linear stability analysis and energy averaging technique, we obtain analytic formulas for the stable boundaries of various states. Then, a phase diagram is constructed, which is controlled by the current and a tunable ratio $\beta$ of the fieldlike torque to the dampinglike one. We find that some new stable, bistable and dynamic states come forth. Especially, a bias-field-free self-oscillation emerges for negative $\beta$, which enables the average energy balance between the dampinglike torque and the intrinsic damping. There occur two kinds of oscillations, analogous to the usual in-plane and out-of-plane precessions. If increasing the current, the frequency declines for the former, and subsequently rises for the latter. Varying $\beta$ slightly affects the frequency range, but dramatically alters the adjustable range of current. In addition, the phase diagram indicates that the switching direction reverses with $\beta$ stepping over $- 1/\alpha$ with $\alpha$ being the damping constant, and the switching current decreases with $\vert \beta \vert$ increasing.

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Switching of Perpendicular Magnetization by Spin–Orbit Torque

Zhu

2023

Advanced Materials

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Magnetic materials with strong perpendicular magnetic anisotropy are of great interest for the development of nonvolatile magnetic memory and computing technologies due to their high stabilities at the nanoscale. However, electrical switching of such perpendicular magnetization in an energy-efficient, deterministic, scalable manner has remained a big challenge. This problem has recently attracted enormous efforts in the field of spintronics. Here, we review recent advances and challenges in the understanding of the electrical generation of spin currents, the switching mechanisms and the switching strategies of perpendicular magnetization, the switching current density by spin-orbit torque of transverse spins, the choice of perpendicular magnetic materials, and summarize the progress in prototype perpendicular SOT memory and logic devices toward the goal of energy-efficient, dense, fast perpendicular spin-orbit torque applications.

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Strong Spin-Orbit Torque Induced by the Intrinsic Spin Hall Effect in Cr1−xPtx

Cited by 10 publications

References 60 publications

Giant, Linearly Increasing Spin–Orbit Torque Efficiency in Symmetry-Broken Spin–Orbit Torque Superlattices

Giant, Linearly Increasing Spin–Orbit Torque Efficiency in Symmetry-Broken Spin–Orbit Torque Superlattices

Field-free self-oscillation of magnetization enabled by the fieldlike spin-orbit torque

Switching of Perpendicular Magnetization by Spin–Orbit Torque

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