Giant Damping-like Torque Efficiency via Synergistic Spin Hall and enhanced Orbital Hall Effects

Bilal Jamshed; Go Dong Wook; Ramu Maddu; Sabpreet Bhatti; S.N. Piramanayagam; Subhakanta Das

REVIEW 4 major objections 5 minor 55 references

Giant Damping-like Torque Efficiency via Synergistic Spin Hall and enhanced Orbital Hall Effects

T0 review · 4 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read Adding a 2 nm NiW seedlayer doubles the orbital-Hall torque contribution from a Ru layer.

desk verdict Useful experiment, overclaimed mechanism: NiW seedlayer improves SOT efficiency, but the M4/M5 comparison doesn't isolate texture from other NiW effects. read the letter →

arxiv 2507.17372 v1 pith:3QM3BDME submitted 2025-07-23 physics.app-ph cond-mat.mes-hall

Subhakanta Das , Sabpreet Bhatti , Ramu Maddu , Bilal Jamshed , Go Dong Wook , S.N. Piramanayagam This is my paper · ORCID

classification physics.app-phcond-mat.mes-hall

keywords orbitalHalleffectspinspin-orbittorqueRuhcp(002)textureNiWseedlayerdamping-likeefficiencyperpendicularmagneticanisotropymagnetizationswitching

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper tries to establish that the crystallographic texture of an orbital-Hall layer is a controllable lever for spin-orbit torque. By inserting a 2 nm NiW seedlayer beneath a Ru layer, the hcp(002) texture improves, and the inferred orbital-Hall contribution to the effective damping-like torque efficiency $\xi_{DL}^{E}$ roughly doubles. With Pt providing both spin-Hall current and orbital-to-spin conversion, the full stack reaches about 1.4 times the efficiency of a Pt(4 nm) reference and switches at a 1.2-fold lower current density. The claim matters because it points to texture engineering, not only material choice, as a way to make orbital Hall effects useful in spintronic devices.

What carries the argument

The load-bearing object is the Ru hcp(002) crystallographic texture, promoted by a NiW seedlayer adopted from hard-disk media technology. The mechanism is the orbital Hall effect in Ru, which generates an orbital current that a Pt layer with strong spin-orbit coupling converts into spin current, while Pt also contributes its own spin Hall current. The measured quantity is the damping-like torque efficiency $\xi_{DL}^{E}=(2e/\hbar)M_{S}t_{FM}(\mu_0 H_{SOT}/E)$, obtained from current-induced loop shifts and corroborated by second-harmonic Hall measurements.

What would settle it

A control stack with NiW present but no bottom Ru layer should show no comparable rise in damping-like torque efficiency; if it does, the boost comes from the seedlayer's other effects rather than from Ru texture.

Watch

Extended reading notes

Core claim

The central claim is that a 2 nm NiW underlayer improves the Ru hcp(002) texture and thereby doubles the orbital-Hall contribution to the effective damping-like torque efficiency: the disentangled OHE contribution rises from $0.39\times10^{5}\,\Omega^{-1}\text{m}^{-1}$ in the untextured stack to $0.81\times10^{5}\,\Omega^{-1}\text{m}^{-1}$ in the textured one. In the optimized Pt(2.5 nm) stack, the combined spin-Hall and orbital-Hall torque reaches about 1.4 times the $\xi_{DL}^{E}$ of a Pt(4 nm) reference, and current-induced switching shows about a 1.2-fold reduction in switching current density. XRD supports the texture story: adding NiW strengthens and slightly shifts the Ru hcp(002) peak, and also sharpens the Pt(111) and Co(002) peaks.

Load-bearing premise

The M4-versus-M5 comparison assumes that adding 2 nm of NiW changes only the Ru texture; in reality it also changes the underlayer material, interface quality, Pt/Co growth, and current distribution, and no control sample with NiW but without Ru isolates those effects.

Editorial extensions

If this is right

Texturing an orbital-Hall metal with a seedlayer is a practical route to raise $\xi_{DL}^{E}$ beyond what spin Hall metals alone provide.
The Pt thickness has an optimum near 2.5 nm for orbital-to-spin conversion; thicker Pt diffuses the converted spin current and leaves only the spin Hall contribution.
The optimized textured stack cuts switching current density by about 1.2 times relative to a Pt-only reference at similar perpendicular anisotropy.
Annealing at 300 °C leaves the textured stack's torque efficiency essentially unchanged, which the authors read as CMOS-compatible thermal stability.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

If texture is the active ingredient, other hcp(002)-promoting seedlayers or epitaxial Ru should raise the orbital-Hall torque further; that is a directly testable prediction the paper does not make.
The 2-fold OHE enhancement is inferred by subtracting two full stacks, so a NiW-only control would separate texture from underlayer and interface effects.
The same Ru/Pt synergy could be tried with other orbital-Hall metals such as Nb, Zr, or Ti to see whether seedlayer texture engineering generalizes beyond Ru.
A NiW thickness series would show whether the torque gain saturates once Ru(002) texture is fully developed, giving a design rule for SOT stacks.

Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Colleague, here's the short version: this is a useful experimental paper with a promising idea, but the headline mechanism—that NiW enhances orbital Hall torque through Ru texture—is not established by the data as presented. The practical result (better torque efficiency, lower switching current) looks real; the attribution does not.

What's actually new: applying the hard-disk NiW seedlayer trick to an orbital Hall stack, and the effect is reproducible across two measurement techniques (loop shift and harmonic) that agree in ranking. The device optimization is sensible; the Pt-thickness series gives a 1.4x improvement in torque efficiency over Pt(4) and a 1.2x lower switching current, with harmonic measurements consistent. As an engineering route to SOT-MRAM, the result is plausible and the paper is readable.

Now the soft spots. The M4/M5 comparison lacks a control that isolates texture. NiW is a W-based alloy with potentially large spin Hall and orbital Hall conductivities; it sits in the current path, so some or all of the increased torque could be a direct NiW contribution, not enhanced Ru OHE. The XRD also shows NiW increases Pt(111) and Co(002) peaks, and Pt SHE is texture-sensitive, so the Pt contribution can change independently. The phrase 'clearly indicates' overstates this. Second, the OHE/SHE decomposition is deferred to supplementary, but the main text uses a 2-fold figure from that decomposition; ratios are quoted without uncertainties. Third, the annealing section contradicts the abstract: the abstract says no appreciable change, while Section 6 reports significant reductions for M2, M4, and M5. These are fixable issues, not a dead end.

Who it's for: experimental spintronics/orbitronics groups working on SOT-MRAM. A referee should ask for the NiW-only control (or an inert seedlayer control), uncertainty propagation, and a consistent annealing narrative. The paper deserves serious refereeing because the data are real, the idea is fresh, and the practical metrics are useful even if the texture mechanism remains unproven.

Referee Report

4 major / 5 minor

Summary. The manuscript reports damping-like torque efficiency measurements in Ru/Pt/Co heterostructures, with a NiW seed layer used to improve the hcp(002) texture of Ru. Comparing stacks M4 (Ta/Ru/Pt/Co without NiW) and M5 (Ta/NiW/Ru/Pt/Co), the authors report a roughly twofold increase in the extracted OHE contribution to the effective damping-like torque efficiency and up to a 1.4-fold larger full-stack efficiency relative to a Pt(4 nm) reference. Series N optimizes Pt thickness and shows a 1.2-fold reduction in switching current density compared with the reference. The conclusions assign the M4-to-M5 improvement to enhanced orbital Hall torque from improved Ru texture, supplemented by synergistic SHE from Pt. The paper includes loop-shift and second-harmonic electrical measurements, XRD, VSM, and annealing studies.

Significance. If the texture-driven OHE enhancement is correct, the result is significant for orbitronics and SOT device engineering: it would show that crystallographic texture, not only material choice, controls orbital Hall torque. A genuine strength is that two independent electrical measurement techniques (loop-shift and harmonic) agree in the ranking of samples, which supports a real torque enhancement. The manuscript also reports a practical switching-current reduction and thermal-stability data. However, the central attribution to Ru texture is not established by the presented evidence, because the NiW seed introduces multiple simultaneous changes and no appropriate control is shown; the OHE/SHE decomposition on which the twofold claim rests is deferred to a supplementary file and reported without uncertainties. The paper should be revised to address these load-bearing issues before the claimed mechanism can be accepted.

major comments (4)

[Section 3, Table 1, Figure 1d] The central claim that improved Ru hcp(002) texture doubles the OHE contribution rests entirely on the M4-versus-M5 comparison, but adding the 2 nm NiW seed changes the Ta/NiW/Ru interface, the current distribution through the stack, and the crystallinity of the Pt and Co layers simultaneously. In fact, Figure 1d shows that the Pt fcc(111) and Co hcp(002) peaks also intensify in M5, so a texture-dependent change in Pt SHE or a direct NiW spin/orbital torque is equally consistent with the data. Without a control sample containing NiW but no Ru, or a separate measurement in which Ru texture is improved by an inert seed, the phrase 'clearly indicates the role of crystallographic texture on the OHE enhancement' (Section 3) overstates what the experiment establishes.
[Section 3] The quantitative basis of the twofold claim is the decomposition that yields OHE contributions of 0.39 x 10^5 and 0.81 x 10^5 ohm^-1 m^-1 for M4 and M5, but this decomposition is only described as being 'in supplementary,' and no uncertainties are reported anywhere for these values or for the fold-enhancement ratios. Since the paper's central message depends on this subtraction model, the main text must show the explicit decomposition equations, the literature values used, the sign conventions, and the error propagation. As written, the reader cannot verify whether the reported twofold OHE increase is robust or an artifact of the model.
[Section 6 and Abstract/Conclusions] The abstract and the conclusions state that 'no appreciable change' in spin-orbit torque efficiency is found after annealing, but Section 6 reports 'a significant reduction' for M2, M4, and M5 and a slight reduction for M1 and M3. This is an internal inconsistency that must be reconciled. The statement about M5 being 'comparable' is also difficult to evaluate because Figure 6 does not include error bars; please state clearly which samples changed and by how much.
[Equation (1)] Equation (1) uses t_FM and the effective field per applied electric field, without correcting for how the current is distributed among the Ta, NiW, Ru, and Pt layers. Since M5 adds a conductive NiW underlayer, changes in current shunting between M4 and M5 can alter the measured efficiency independently of any texture effect on the OHE. The authors should either include a shunting correction (e.g., resistivity-weighted layer currents) or explicitly justify why the unweighted E normalization is adequate for the M4-versus-M5 comparison.

minor comments (5)

[Section 3] The text refers to 'Figure 4d' when describing the SOT-field versus current plot; this appears to be a typo for Figure 2d.
[Section 3] The text refers to 'Figure 3d' for the plot of efficiency versus Pt thickness, but the figure caption only defines panels (a) and (b); the intended reference is likely Figure 3b.
[Throughout] The paper repeatedly cites 'supplementary' for M1/M2 loop-shift results, the OHE/SHE separation, annealed XRD, and series-N characterization, but the supplementary file is not included in the reviewed version. Please either include it with the revision or move the essential material into the main text.
[Figure 2f] Figure 2f reports efficiency values without error bars, and the text gives fold-enhancement ratios without uncertainties; adding error bars or confidence intervals would make the claimed enhancements more convincing.
[Section 8] The second-harmonic description says the first-harmonic fit uses Equation (2) and the second-harmonic fit uses an equation displayed inline; it would help to label that fitting equation as an equation number for reproducibility.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the torque efficiency is measured independently and the OHE/SHE decomposition is an empirical subtraction model, not a definitional fit.

full rationale

The central quantity ξ_DL^E is obtained from measured loop shifts using Eq. (1) and cross-checked by second-harmonic measurements; it is not fitted to produce the claimed enhancement. The separation into SHE and OHE contributions is a subtraction model based on nominally identical stacks (M3 vs M4 vs M5), which involves physical assumptions about what changes between stacks, but those assumptions are not a definitional identity: XRD (Fig. 1d) independently shows the NiW seed changes Ru, Pt, and Co texture, and the torque comparison is an empirical ratio, not a parameter forced by the analysis. Self-citations (NiW seedlayer refs 29–30, measurement protocol ref 34, orbitronics refs 14/27) are either supported by in-paper measurements or are standard external results, and no uniqueness claim is imported to forbid alternatives. The M4-vs-M5 comparison is confounded (NiW also alters Pt/Co texture and adds a W-alloy layer in the current path), which is a validity threat, but not circular bookkeeping. The annealing discrepancy between the abstract and Section 6 is an internal inconsistency, not a circular step. Score 0.

Assumptions & free parameters 0 free parameters · 4 assumptions · 0 invented entities

No new entities or fit constants are introduced. The causal inference rests on treating NiW as a texture-only change and on the standard orbital-Hall-to-spin conversion picture. The key assumption, that NiW acts only through Ru texture, is central and unchecked.

assumptions (4)

domain assumption OHE in Ru generates an orbital current that is converted to spin current by an adjacent Pt layer, contributing to damping-like torque.
Section 1 and Figure 1a; the conversion mechanism is assumed from prior literature and is not directly verified in this stack.
ad hoc to paper The NiW underlayer in M5 affects the measured torque only by improving Ru texture and the resulting OHE, with no independent torque contribution and no changes to current shunting.
The M4 vs M5 comparison assumes the entire 2-fold increase in the disentangled OHE component comes from texture; no NiW-only control is provided (Table 1).
domain assumption In M3, the top Ru layer does not contribute to the measured damping-like torque, so M3 isolates Pt SHE.
Section 3 states the top Ru has low SHC and its OHE cannot interact with Co magnetisation.
domain assumption Loop-shift and second-harmonic methods return the damping-like SOT field in these perpendicular stacks.
Section 3 references standard methods (refs 33 and 34) without further validation on these specific stacks.

how reviews work

0 comments

Cite this review

Pith. "Pith review of Giant Damping-like Torque Efficiency via Synergistic Spin Hall and enhanced Orbital Hall Effects." pith.science (2026). https://pith.science/paper/3QM3BDME

@misc{pith2026250717372,
  author       = {Pith},
  title        = {Pith review of: Giant Damping-like Torque Efficiency via Synergistic Spin Hall and enhanced Orbital Hall Effects},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/3QM3BDME}},
  note         = {Machine review of arXiv:2507.17372}
}

read the original abstract

Current-induced spin-orbit torque (SOT) has emerged as a promising method for achieving energy-efficient magnetisation switching in advanced spintronic devices. Over the past two decades, researchers have primarily focused on enhancing spin current generation through the spin Hall effect, relying predominantly on the spin degree of freedom (DoF) of the electron, while neglecting its orbital counterpart. Orbital Hall effect depends critically on the crystallinity and the interface between the orbital Hall layer and the orbital-to-spin conversion layer. However, most experimental works on orbital Hall effect relied on polycrystalline films with no special attention to improve the crystallographic texture. In this work, we have grown the Ru layer on a NiW seedlayer, which helped to improve the crystallographic texture, thereby enhancing the switching efficiency by over 44%. Such a huge increase in switching efficiency was achieved by (i) improving crystallographic texture and (ii) leveraging both spin and orbital DoFs. Our study underscores the potential for improving the spin-torque efficiency by combining interface engineering, orbital and spin Hall effects to drive next-generation spintronics.

Figures

Figures reproduced from arXiv: 2507.17372 by the authors.

**Figure 1.** (a) Schematic representations of IOH and ISH generation in Ru/Pt/Co heterostructure. IOH (as represented by red arrows) is generated by the strong OHE in the Ru layer. The strong SOC of the Pt layer converts the IOH coming from the Ru layer to ISH (blue arrows). Simultaneously, the Pt layer also generates an ISH (relatively smaller blue arrows) via the SHE. Then both the ISH (one generated via the SHE and the one co… view at source ↗

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

55 extracted references · 54 canonical work pages

[1]

Introduction The advancement of emerging spintronic devices relies on the ability to control their magnetisation in a reliable and energy -efficient manner. Over the past few decades, the spin Hall effect has emerged as an efficient approach for ultra-fast magnetisation switching in heavy metal (HM)/ferromagnetic (FM) heterostructures 1–6. In SHE, a charg...

work page
[2]

Series M was engineered to understand the role of Ru hcp (002) texture on the OHE aided by a constant Pt layer in converting OHE -SHE in heterostructure stacks

Thin-film Deposition and Characterisation As shown in Table 1, we deposited two series of thin film samples - series M and N. Series M was engineered to understand the role of Ru hcp (002) texture on the OHE aided by a constant Pt layer in converting OHE -SHE in heterostructure stacks . The series N was aimed at maximising the resultant switching efficien...

work page
[3]

Figure 2a shows an optical microscopic image of the device with a schematic of the electrical setup

Loop-shift measurements Sample Series-M We carried out current-induced loop shift measurements on Hall bar devices with lateral dimensions of 10 μm × 60 μm to calculate the 𝜉𝐷𝐿 𝐸 33,34. Figure 2a shows an optical microscopic image of the device with a schematic of the electrical setup. For the purpose of discussion, we present here the loop shift measurem...

work page
[4]

We used Hall cross devices of the reference sample and a series N sample with t Pt = 2.5 nm (which has maximum 𝜉𝐷𝐿 𝐸 ) for the measurements

Current-induced Magnetisation Switching Measurements Next, we performed current-induced magnetisation switching measurements to calculate switching current density (JSW). We used Hall cross devices of the reference sample and a series N sample with t Pt = 2.5 nm (which has maximum 𝜉𝐷𝐿 𝐸 ) for the measurements. We started the measurements by saturating the...

work page
[5]

For more details on the measurement protocol, see the methods section

Harmonic measurements To validate the results obtained from the loop shift measurements, we performed AC harmonic Hall voltage measurements on a Hall cross-device with dimensions of 5 × 30 μm2 to estimate 𝜉𝐷𝐿 𝐸 . For more details on the measurement protocol, see the methods section. We performed AHE measurements to calculate anomalous Hall resistance . To...

work page
[6]

Therefore, it is essential to investigate the effect of temperature on 𝜉𝐷𝐿 𝐸

Effect of Annealing on the OHE 11 In the production of MRAM, the magnetic tunnel junctions go through heat treatments to improve the crystallisation of CoFeB and during the packaging 42. Therefore, it is essential to investigate the effect of temperature on 𝜉𝐷𝐿 𝐸 . For this purpose, we annealed the series M samples in a high vacuum chamber (2 × 10-8 Torr)...

work page
[7]

Further, we have carried out a quantitative analysis to disentangle the individual contributions of both effects

Conclusions In summary, we study the influence of Ru hcp (002) texture on the enhancement of OHE arising from Ru and report a giant damping-like torque efficiency by leveraging both SHE and OHE concurrently. Further, we have carried out a quantitative analysis to disentangle the individual contributions of both effects. In a separate study, we maximised t...

work page
[8]

In contrast, sample M2 exhibits only OHE, attributed to the strong OHC of the top Ru layer

Co(1.1) Ru(2) 4 From symmetry considerations, sample M1 is not expected to exhibit SHE or the OHE. In contrast, sample M2 exhibits only OHE, attributed to the strong OHC of the top Ru layer. In this configuration, the top Pt layer serves as an intermediate conversion layer, transforming the IOH-to-ISH, which subsequently interacts with the magnetisation o...

work page

Show all 55 references

[9]

The substrates were sequentially cleaned by ultrasonication in acetone, isopropyl alcohol and deionised water for 2 minutes each

Methodology Thin film deposition We deposited all the samples mentioned in Table 1 using a DC/RF magnetron sputtering system on a Si/SiO2 substrate. The substrates were sequentially cleaned by ultrasonication in acetone, isopropyl alcohol and deionised water for 2 minutes each...
[10]

Liu, L. et al. Spin-Torque Switching with the Giant Spin Hall Effect of Tantalum. Science 336, 555–558 (2012)

2012
[11]

Fan, X. et al. Quantifying interface and bulk contributions to spin–orbit torque in magnetic bilayers. Nature Communications 5, 3042 (2014)

2014
[12]

Ishikawa, T. et al. Large intrinsic spin Hall conductivity in orthorhombic tungsten. Phys. Rev. Materials 7, (2023)

2023
[13]

Bhatti, S. et al. Spintronics based random access memory: a review. Materials Today 20, 530–548 (2017)

2017
[14]

Manchon, A. et al. Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems. Rev. Mod. Phys. 91, 035004 (2019)

2019
[15]

Shao, Q. et al. Roadmap of Spin–Orbit Torques. IEEE Transactions on Magnetics 57, 1– 39 (2021)

2021
[16]

Spin Hall Effects in Metals

Hoffmann, A. Spin Hall Effects in Metals. IEEE Trans. Magn. 49, 5172–5193 (2013)

2013
[17]

O., Wunderlich, J., Back, C

Sinova, J., Valenzuela, S. O., Wunderlich, J., Back, C. H. & Jungwirth, T. Spin Hall effects. Rev. Mod. Phys. 87, 1213–1260 (2015)

2015
[18]

Wang, H. L. et al. Scaling of Spin Hall Angle in 3d, 4d, and 5d Metals fromY3Fe5O12/Metal Spin Pumping. Phys. Rev. Lett. 112, (2014)

2014
[19]

J., Gudmundsen, T

Liu, L., Lee, O. J., Gudmundsen, T. J., Ralph, D. C. & Buhrman, R. A. Current-Induced Switching of Perpendicularly Magnetized Magnetic Layers Using Spin Torque from the Spin Hall Effect. Phys. Rev. Lett. 109, (2012)

2012
[20]

Takeuchi, Y . et al. Spin-orbit torques in high-resistivity-W/CoFeB/MgO. Applied Physics Letters 112, 192408 (2018). 14

2018
[21]

& Zhang, X

Chen, W., Xiao, G., Zhang, Q. & Zhang, X. Temperature study of the giant spin Hall effect in the bulk limit of $\ensuremath{\beta}\ensuremath{-}\mathrm{W}$. Phys. Rev. B 98, 134411 (2018)

2018
[22]

Tanaka, T. et al. Intrinsic spin Hall effect and orbital Hall effect in 4 d and 5 d transition metals. Phys. Rev. B 77, 165117 (2008)

2008
[23]

& Lee, H.-W

Go, D., Jo, D., Kim, C. & Lee, H.-W. Intrinsic Spin and Orbital Hall Effects from Orbital Texture. Phys. Rev. Lett. 121, (2018)

2018
[24]

& Oppeneer, P

Salemi, L. & Oppeneer, P. M. First-principles theory of intrinsic spin and orbital Hall and Nernst effects in metallic monoatomic crystals. Phys. Rev. Materials 6, (2022)

2022
[25]

Zheng, Z. C. et al. Magnetization switching driven by current-induced torque from weakly spin-orbit coupled Zr. Phys. Rev. Research 2, (2020)

2020
[26]

Yang, Y . et al. Orbital torque switching in perpendicularly magnetized materials. Nat Commun 15, 8645 (2024)

2024
[27]

Choi, Y .-G. et al. Observation of the orbital Hall effect in a light metal Ti. Nature 619, 52–56 (2023)

2023
[28]

Hayashi, H. et al. Observation of long-range orbital transport and giant orbital torque. Commun Phys 6, (2023)

2023
[29]

B., Aon, S

Mahapatra, D., Bhunia, H., Miah, A. B., Aon, S. & Mitra, P. Evidence of orbital Hall current-induced correlation in second-harmonic response of longitudinal and transverse voltage in light metal–ferromagnet bilayers. Applied Physics Letters 126, (2025)

2025
[30]

Ding, S. et al. Harnessing Orbital-to-Spin Conversion of Interfacial Orbital Currents for Efficient Spin-Orbit Torques. Phys. Rev. Lett. 125, (2020)

2020
[31]

Tazaki, Y . et al. Current-induced torque originating from orbital current. Preprint at https://doi.org/10.48550/arXiv.2004.09165 (2020). 15

2020 doi arXiv
[32]

Lee, S. et al. Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching. Commun Phys 4, 1–6 (2021)

2021
[33]

Gupta, R. et al. Harnessing orbital Hall effect in spin-orbit torque MRAM. Nat Commun 16, 130 (2025)

2025
[34]

Bose, A. et al. Detection of long-range orbital-Hall torques. Phys. Rev. B 107, 134423 (2023)

2023
[35]

Wang, P. et al. Orbitronics: Mechanisms, Materials and Devices. Adv Elect Materials 11, 2400554 (2025)

2025
[36]

& Mokrousov, Y

Go, D., Jo, D., Lee, H.-W., Kläui, M. & Mokrousov, Y . Orbitronics: Orbital currents in solids. EPL 135, 37001 (2021)

2021
[37]

Lee, D. et al. Orbital torque in magnetic bilayers. Nat Commun 12, 6710 (2021)

2021
[38]

Piramanayagam, S. N. et al. Writability Improvement in Perpendicular Recording Media Using Crystalline Soft Underlayer Materials. IEEE Trans. Magn. 49, 758–764 (2013)

2013
[39]

K., Wong, S

Yang, Y ., Varghese, B., Tan, H. K., Wong, S. K. & Piramanayagam, S. N. Microstructure investigations of hcp phase CoPt thin films with high coercivity. Journal of Applied Physics 115, (2014)

2014
[40]

Liu, E. et al. Seed layer impact on structural and magnetic properties of [Co/Ni] multilayers with perpendicular magnetic anisotropy. Journal of Applied Physics 121, 043905 (2017)

2017
[41]

Zhu, Z. et al. Annealing effect and interlayer modulation on magnetic damping of CoFeB/interlayer/Pt thin films. Applied Physics Letters 113, (2018)

2018
[42]

Pai, C.-F., Mann, M., Tan, A. J. & Beach, G. S. D. Determination of spin torque efficiencies in heterostructures with perpendicular magnetic anisotropy. Phys. Rev. B 93, 144409 (2016). 16

2016
[43]

Bhatti, S. et al. Enhancing damping-like efficiency by low-energy mixed ions bombardment. Applied Physics Letters 124, 022407 (2024)

2024
[44]

Li, S. H. et al. Tuning the spin-orbit torque effective fields by varying Pt insertion layer thickness in perpendicularly magnetized Pt/Co/Pt(t)/Ta structures. Journal of Magnetism and Magnetic Materials 473, 394–398 (2019)

2019
[45]

Zhu, L., Ralph, D. C. & Buhrman, R. A. Maximizing spin-orbit torque generated by the spin Hall effect of Pt. Applied Physics Reviews 8, 031308 (2021)

2021
[46]

& Yang, H

Qiu, X., Shi, Z., Fan, W., Zhou, S. & Yang, H. Characterization and Manipulation of Spin Orbit Torque in Magnetic Heterostructures. Advanced Materials 30, 1705699 (2018)

2018
[47]

Dunne, P. et al. Helium Ion Microscopy for Reduced Spin Orbit Torque Switching Currents. Nano Lett. 20, 7036–7042 (2020)

2020
[48]

Fan, Y . et al. Magnetization switching through giant spin–orbit torque in a magnetically doped topological insulator heterostructure. Nature Mater 13, 699–704 (2014)

2014
[49]

& Hai, P

Shirokura, T. & Hai, P. N. Angle resolved second harmonic technique for precise evaluation of spin orbit torque in strong perpendicular magnetic anisotropy systems. Applied Physics Letters 119, (2021)

2021
[50]

Wu, H. et al. Room-Temperature Spin-Orbit Torque from Topological Surface States. Phys. Rev. Lett. 123, 207205 (2019)

2019
[51]

Ikeda, S. et al. A perpendicular-anisotropy CoFeB–MgO magnetic tunnel junction. Nature Mater 9, 721–724 (2010)

2010
[52]

& Liang, K

Lee, H.-Y ., Hsieh, Y .-W., Hsu, C.-H. & Liang, K. S. Characteristics of sputter-deposited Ru thin films on Si substrates. Materials Chemistry and Physics 82, 984–990 (2003)

2003
[53]

& Wang, Y .-L

Wu, C.-Y ., Lee, W.-H., Chang, S.-C., Cheng, Y .-L. & Wang, Y .-L. Effect of Annealing on the Microstructure and Electrical Property of RuN Thin Films. J. Electrochem. Soc. 158, H338 (2011). 17

2011
[54]

Hayes, M. et al. Improved properties of atomic layer deposited ruthenium via postdeposition annealing. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 39, (2021)

2021
[55]

Wells, A. W. J., Shepley, P. M., Marrows, C. H. & Moore, T. A. Effect of interfacial intermixing on the Dzyaloshinskii-Moriya interaction in Pt/Co/Pt. Phys. Rev. B 95, 054428 (2017)

2017

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.

[1] [1]

Introduction The advancement of emerging spintronic devices relies on the ability to control their magnetisation in a reliable and energy -efficient manner. Over the past few decades, the spin Hall effect has emerged as an efficient approach for ultra-fast magnetisation switching in heavy metal (HM)/ferromagnetic (FM) heterostructures 1–6. In SHE, a charg...

work page

[2] [2]

Series M was engineered to understand the role of Ru hcp (002) texture on the OHE aided by a constant Pt layer in converting OHE -SHE in heterostructure stacks

Thin-film Deposition and Characterisation As shown in Table 1, we deposited two series of thin film samples - series M and N. Series M was engineered to understand the role of Ru hcp (002) texture on the OHE aided by a constant Pt layer in converting OHE -SHE in heterostructure stacks . The series N was aimed at maximising the resultant switching efficien...

work page

[3] [3]

Figure 2a shows an optical microscopic image of the device with a schematic of the electrical setup

Loop-shift measurements Sample Series-M We carried out current-induced loop shift measurements on Hall bar devices with lateral dimensions of 10 μm × 60 μm to calculate the 𝜉𝐷𝐿 𝐸 33,34. Figure 2a shows an optical microscopic image of the device with a schematic of the electrical setup. For the purpose of discussion, we present here the loop shift measurem...

work page

[4] [4]

We used Hall cross devices of the reference sample and a series N sample with t Pt = 2.5 nm (which has maximum 𝜉𝐷𝐿 𝐸 ) for the measurements

Current-induced Magnetisation Switching Measurements Next, we performed current-induced magnetisation switching measurements to calculate switching current density (JSW). We used Hall cross devices of the reference sample and a series N sample with t Pt = 2.5 nm (which has maximum 𝜉𝐷𝐿 𝐸 ) for the measurements. We started the measurements by saturating the...

work page

[5] [5]

For more details on the measurement protocol, see the methods section

Harmonic measurements To validate the results obtained from the loop shift measurements, we performed AC harmonic Hall voltage measurements on a Hall cross-device with dimensions of 5 × 30 μm2 to estimate 𝜉𝐷𝐿 𝐸 . For more details on the measurement protocol, see the methods section. We performed AHE measurements to calculate anomalous Hall resistance . To...

work page

[6] [6]

Therefore, it is essential to investigate the effect of temperature on 𝜉𝐷𝐿 𝐸

Effect of Annealing on the OHE 11 In the production of MRAM, the magnetic tunnel junctions go through heat treatments to improve the crystallisation of CoFeB and during the packaging 42. Therefore, it is essential to investigate the effect of temperature on 𝜉𝐷𝐿 𝐸 . For this purpose, we annealed the series M samples in a high vacuum chamber (2 × 10-8 Torr)...

work page

[7] [7]

Further, we have carried out a quantitative analysis to disentangle the individual contributions of both effects

Conclusions In summary, we study the influence of Ru hcp (002) texture on the enhancement of OHE arising from Ru and report a giant damping-like torque efficiency by leveraging both SHE and OHE concurrently. Further, we have carried out a quantitative analysis to disentangle the individual contributions of both effects. In a separate study, we maximised t...

work page

[8] [8]

In contrast, sample M2 exhibits only OHE, attributed to the strong OHC of the top Ru layer

Co(1.1) Ru(2) 4 From symmetry considerations, sample M1 is not expected to exhibit SHE or the OHE. In contrast, sample M2 exhibits only OHE, attributed to the strong OHC of the top Ru layer. In this configuration, the top Pt layer serves as an intermediate conversion layer, transforming the IOH-to-ISH, which subsequently interacts with the magnetisation o...

work page