High‐Efficiency Spin–Orbit Torque Switching Using a Single Heavy‐Metal Alloy with Opposite Spin Hall Angles

Bekele, Zelalem Abebe; Liu, Xionghua; Cao, Yi; Wang, Kaiyou

doi:10.1002/aelm.202000793

Cited by 36 publications

(40 citation statements)

References 52 publications

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“…This is exploited to switch the magnetization of an attached layer of Co by SOT. [44] According to our results, a GdFeCo/Cu bilayer should be even more effective for the global generation of spin current, SHE-like plus SAHE-like. We also suggest that the switching of a magnetic layer deposited on GdFeCo/Cu could take advantage not only on the intensity of the spin current emission by GdFeCo/Cu but also on the combination of torques of different symmetries.…”

Section: Effsupporting

confidence: 53%

“…This is a unique information of what can be the relative proportions of the SAHE-like and SHElike symmetries in a magnetic material, respectively about 80% and 20% for the spin currents emitted by GdFeCo/Cu (overall, including bulk and interfacial contributions). We note here that a very recent work [44] has shown the remarkably efficient generation of spin current by other Gd alloys. In GdPt alloys, the corresponding θ SHE reaches values around 0.27, well above the θ SHE of Pt.…”

Section: Effmentioning

confidence: 61%

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Current‐Induced Spin Torques on Single GdFeCo Magnetic Layers

et al. 2021

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A novel direction of spintronics, namely "spin-orbitronics", exploits the spin-orbit coupling (SOC) to generate spin currents, which can then induce spin-orbit torques (SOT) to manipulate magnetization. [1] This opens technological applications such as the three-terminal magnetic random memory Spintronics exploit spin-orbit coupling (SOC) to generate spin currents, spin torques, and, in the absence of inversion symmetry, Rashba and Dzyaloshinskii-Moriya interactions. The widely used magnetic materials, based on 3d metals such as Fe and Co, possess a small SOC. To circumvent this shortcoming, the common practice has been to utilize the large SOC of nonmagnetic layers of 5d heavy metals (HMs), such as Pt, to generate spin currents and, in turn, exert spin torques on the magnetic layers. Here, a new class of material architectures is introduced, excluding nonmagnetic 5d HMs, for high-performance spintronics operations. Very strong current-induced torques exerted on single ferrimagnetic GdFeCo layers, due to the combination of large SOC of the Gd 5d states and inversion symmetry breaking mainly engineered by interfaces, are demonstrated. These "self-torques" are enhanced around the magnetization compensation temperature and can be tuned by adjusting the spin absorption outside the GdFeCo layer. In other measurements, the very large emission of spin current from GdFeCo, 80% (20%) of spin anomalous Hall effect (spin Hall effect) symmetry is determined. This material platform opens new perspectives to exert "self-torques" on single magnetic layers as well as to generate spin currents from a magnetic layer.

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Section: Effsupporting

confidence: 53%

Section: Effmentioning

confidence: 61%

Current‐Induced Spin Torques on Single GdFeCo Magnetic Layers

et al. 2021

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“…[5][6][7] The conventional SOT-based MTJ device is composed of the MTJ device deposited above a nonmagnetic heavy metal (HM) layer. [7][8][9] The writing current flows through the low resistance HM layer rather than directly through the MTJ junction, [9][10][11] thereby increasing the opportunity to improve the read stability and energy consumption. These advantages make SOT-MRAM has much better endurance and is considered as the next-generation non-volatile memory.…”

Section: Tuning the High-efficiency Field-free Current-induced Deterministic Switching Via Ultrathin Ptmo Layer With Mo Contentmentioning

confidence: 99%

“…However, SOT-driven perpendicular magnetization switching generally requires an additional in-plane magnetic field for symmetry breaking, which is a great obstacle for the integration of an in-plane field source into the nanodevices, and it is undesirable for scaling down and practical applications. [11][12][13][14] By far, many approaches have been proposed for attaining a scalable field-free SOT-driven perpendicular magnetization switching such as by substituting the HM with antiferromagnets (AFM) layers like PtMn and IrMn, [12,[15][16] through the localized laser annealing, [17] by interlayer exchange coupling (IEC), [8,[18][19][20] through electric field control method, [21][22] or by an electrically generated strain. [23] Ma et al [24] reported the field-free SOT-driven magnetization switching by competing spin currents via a bilayer made of HMs with opposite spin Hall angles (θ SHA ).…”

Section: Tuning the High-efficiency Field-free Current-induced Deterministic Switching Via Ultrathin Ptmo Layer With Mo Contentmentioning

confidence: 99%

“…To have better energy efficiency, a material with a large effective θ SHA and high conductivity is very crucial to reduce the current density and energy-efficient of magnetization switching. [23][24][25][26][27] A remarkable progress of manipulating the magnetization has been made towards energy-efficiency scheme using such as alloying HM, [11,28] ferrimagnetic-rearearth transition metal alloy, [29][30] two-dimensional van der Waals materials, [31][32][33] and topological insulators (TIs). [1,27,34] Studies have shown that most TI thin films have limited electrical conductivity in the order of ≈10 5 Ω −1 m −1 , [27,34] which is several times lower than that of HMs and their alloys.…”

Section: Tuning the High-efficiency Field-free Current-induced Deterministic Switching Via Ultrathin Ptmo Layer With Mo Contentmentioning

confidence: 99%

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Tuning the High‐Efficiency Field‐Free Current‐Induced Deterministic Switching via Ultrathin PtMo Layer with Mo Content

Bekele

et al. 2021

Adv Elect Materials

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Spin‐orbit torque (SOT)‐based magnetization switching is a promising candidate for the innovation and developments of spintronic devices. However, the necessity of an in‐plane magnetic field to induce deterministic switching is an obstacle to feasibility in practical applications. Here, it is shown that the field‐free current‐induced magnetization switching in a perpendicular magnetized Pt1−xMox/Co/Ru heterostructure with x = 0, 0.04, 0.07, 0.12, and 0.17. Applying an in‐plane charge current through the Pt1−xMox layer, the device can achieve a high‐efficiency field‐free current‐induced magnetization switching with competing spin currents generated from a single Pt1−xMox alloy layer due to opposite spin Hall angles (θSHA) of Pt and Mo atoms and locally induced electric field. Remarkably, the large θSHA of about 0.35 is achieved in the optimal composition of Pt0.88Mo0.12 alloy, which is much higher than that of the pure Pt structure. The results pave the way to resolve the future problems of scalability and thermal stability for SOT‐driven magnetic tunnelling junctions.

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Enhanced Voltage‐Controlled Magnetic Anisotropy and Field‐Free Magnetization Switching Achieved with High Work Function and Opposite Spin Hall Angles in W/Pt/W SOT Tri‐Layers

Chen,

Jia,

Yang

et al. 2024

Adv Funct Materials

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Voltage‐Gated Spin‐Orbit‐Torque (VGSOT) Magnetic Random‐Access Memory (MRAM) is a promising candidate for reducing writing energy and improving writing speed in emerging memory and in‐memory computing applications. However, conventional Voltage Controlled Magnetic Anisotropy (VCMA) approaches are often inefficient due to the low VCMA coefficient at the CoFeB/MgO interface. Additionally, traditional heavy metal/perpendicular magnetic anisotropy (PMA) ferromagnet bilayers require an external magnetic field to overcome symmetry constraints and achieve deterministic SOT switching. Here, a novel and industry‐compatible SOT underlayer for next‐generation VGSOT MRAM by employing a composite heavy metal tri‐layer with a high work function is presented. This approach achieves a VCMA coefficient exceeding 100 fJ V−1m−1 through electron depletion effects, which is ten times larger than that observed with a pure W underlayer. Furthermore, it is demonstrated that this composite heavy metal SOT underlayer facilitates the integration of VCMA with opposite spin Hall angles, enabling field‐free SOT switching in industry‐compatible PMA CoFeB/MgO systems.

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High‐Efficiency Spin–Orbit Torque Switching Using a Single Heavy‐Metal Alloy with Opposite Spin Hall Angles

Cited by 36 publications

References 52 publications

Current‐Induced Spin Torques on Single GdFeCo Magnetic Layers

Current‐Induced Spin Torques on Single GdFeCo Magnetic Layers

Tuning the High‐Efficiency Field‐Free Current‐Induced Deterministic Switching via Ultrathin PtMo Layer with Mo Content

Enhanced Voltage‐Controlled Magnetic Anisotropy and Field‐Free Magnetization Switching Achieved with High Work Function and Opposite Spin Hall Angles in W/Pt/W SOT Tri‐Layers

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