Spin-orbit torques: Materials, mechanisms, performances, and potential applications

Song, Cheng; Zhang, Ruiqi; Liao, Liyang; Zhou, Yongjian; Zhou, Xiaoling; Chen, Ruyi; You, Yunfeng; Chen, Xianzhe; Pan, Feng

doi:10.1016/j.pmatsci.2020.100761

Cited by 168 publications

(96 citation statements)

References 373 publications

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“… 9 Recently, the nonmagnetic layers made of heavy metallic (HM) elements (W, Ta, Pt, and their alloys 10 − 12 ) are extensively studied because of their large spin–orbit coupling (SOC). 13 Such layers combined with ferromagnetic ones (typically Co, CoFeB) are expected to have new spin transport properties related to the SOC, e.g., spin Hall effect (SHE) and Rashba–Edelstein effect (REE). 14 , 15 Although the SHE occurs in a single HM layer, 16 it is detectable in heterostructures with ferromagnets only, such as F/HM bi- 17 and F/HM/F trilayers.…”

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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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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“…Compared to conventional spin-transfer torque, spin-orbit torque is considered as an effective way to drive domain-wall motion and to switch magnetization with lower power consumption 16,17 . So far, SOT-induced magnetization switching has been widely investigated [17][18][19][20][21][22][23][24][25][26] and extensive works have been done to eliminate the assistive magnetic field during SOT-induced magnetization switching with perpendicular magnetic anisotropy, including the design of interlayer exchange coupling 18 , spin-orbit effects with spin-rotation symmetry 20,21 , lateral structural asymmetry 22,23 , in-plane exchange bias 24,25 , and heavy metals with opposite spin Hall angle 26 . Several studies involving magnetization switching of SAF induced by SOT have been reported [27][28][29][30] ; however, a relatively large in-plane magnetic field is needed to break the symmetry.…”

mentioning

confidence: 99%

Reducing Dzyaloshinskii-Moriya interaction and field-free spin-orbit torque switching in synthetic antiferromagnets

et al. 2021

Self Cite

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Perpendicularly magnetized synthetic antiferromagnets (SAF), possessing low net magnetization and high thermal stability as well as easy reading and writing characteristics, have been intensively explored to replace the ferromagnetic free layers of magnetic tunnel junctions as the kernel of spintronic devices. So far, utilizing spin-orbit torque (SOT) to realize deterministic switching of perpendicular SAF have been reported while a large external magnetic field is typically needed to break the symmetry, making it impractical for applications. Here, combining theoretic analysis and experimental results, we report that the effective modulation of Dzyaloshinskii-Moriya interaction by the interfacial crystallinity between ferromagnets and adjacent heavy metals plays an important role in domain wall configurations. By adjusting the domain wall configuration between Bloch type and Néel type, we successfully demonstrate the field-free SOT-induced magnetization switching in [Co/Pd]/Ru/[Co/Pd] SAF devices constructed with a simple wedged structure. Our work provides a practical route for utilization of perpendicularly SAF in SOT devices and paves the way for magnetic memory devices with high density, low stray field, and low power consumption.

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“…Furthermore, there are increasing number of recent reports on the improved manipulations of local magnetic ordering state of AFM material employing the applications of electric current, [ 24 , 25 , 26 , 27 , 28 , 29 ] mechanical strain, [ 30 , 31 ] optical light with helicity, [ 32 ] and electric field. [ 33 , 34 ] Recent demonstration of AFM Néel vector switching by current‐induced spin‐orbit torque (SOT) in various AFM systems [ 35 ] has received increased attentions, and been found to be particularly interesting as well as useful. It was reported that the electrical manipulating Néel order of AFM by SOT could be realized through two possible mechanisms attributed to field‐like torque in AFM CuMnAs [ 24 ] and Mn 2 Au, [ 36 ] and damping‐like torque exerted by the polarized spin sources from heavy metal (HM) Pt layer due to a spin Hall effect (SHE) in Pt/AFM bilayers system such as Pt/CoO, [ 37 ] Pt/NiO, [ 38 , 39 ] Pt/ α ‐Fe 2 O 3 , [ 40 ] Pt/Mn 2 Au, [ 41 ] and Pt/Mn 3 Sn.…”

Section: Resultsmentioning

confidence: 99%

Programmable Dynamics of Exchange‐Biased Domain Wall via Spin‐Current‐Induced Antiferromagnet Switching

Kim

Moon

et al. 2021

Advanced Science

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Magnetic domain wall (DW) motion in perpendicularly magnetized materials is drawing increased attention due to the prospect of new type of information storage devices, such as racetrack memory. To augment the functionalities of DW motion-based devices, it is essential to improve controllability over the DW motion. Other than electric current, which is known to induce unidirectional shifting of a train of DWs, an application of in-plane magnetic field also enables the control of DW dynamics by rotating the DW magnetization and consequently modulating the inherited chiral DW structure. Applying an external bias field, however, is not a viable approach for the miniaturization of the devices as the external field acts globally. Here, the programmable exchange-coupled DW motion in the antiferromagnet (AFM)/ferromagnet (FM) system is demonstrated, where the role of an external in-plane field is replaced by the exchange bias field from AFM layer, enabling the external field-free modulations of DW motions. Interestingly, the direction of the exchange bias field can also be reconfigured by simply injecting spin currents through the device, enabling electrical and programmable operations of the device. Furthermore, the result inspires a prototype DW motion-based device based on the AFM/FM heterostructure, that could be easily integrated in logic devices.

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Spin-orbit torques: Materials, mechanisms, performances, and potential applications

Cited by 168 publications

References 373 publications

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

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

Reducing Dzyaloshinskii-Moriya interaction and field-free spin-orbit torque switching in synthetic antiferromagnets

Programmable Dynamics of Exchange‐Biased Domain Wall via Spin‐Current‐Induced Antiferromagnet Switching

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