Spin-orbit torque based magnetization switching in Pt/Cu/[Co/Ni]5 multilayer structures

Ostwal, Vaibhav; Penumatcha, Ashish V.; Hung, Yu-Ming; Kent, Andrew D.; Appenzeller, Joerg

doi:10.1063/1.4994711

Cited by 7 publications

(2 citation statements)

References 27 publications

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“…Cu is considered to be a popular spacer for the spin source/FM system due to its long spin diffusion length and high transparency for spins. [ 7,8,11,37 ] We further note that the enhancement of ξ SH by the Cu insertion in the Ni 0.05 Co 0.95 Si film is larger than that in the Ni 0.15 Co 0.85 Si sample. This can be interpreted as the different spin mixing conductance at each interface by different amounts of dopants.…”

Section: Resultsmentioning

confidence: 74%

Elemental Doping and Interface Effects on Spin–Orbit Torques in CoSi‐Based Topological Semimetal Thin Films

Wen

Seki

et al. 2022

Adv Materials Inter

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This work reports on Ni and Fe doping and interface effects on spin–orbit torques (SOTs) generated from a topological semimetal CoSi. CoSi thin films grown on Al2O3(0001) substrates by magnetron co‐sputtering show the B20 structure with a texture in the [210] orientation even after Ni or Fe doping. The SOTs from the films exerted on the magnetization of a CoFeB layer are evaluated by harmonic Hall and spin‐torque ferromagnetic resonance measurements. The spin Hall efficiency ξSH of the textured B20‐CoSi at room temperature is determined to be 9.6%, which decreases to 1.8% for Ni0.15Co0.85Si and to 5.5% for Fe0.26Co0.74Si. The electrical conductivity dependence of the spin Hall conductivity is assigned to the regime of intrinsic mechanism of spin Hall effect, suggesting that the reduction of ξSH with the element doping can be due to the degradation in topological electronic structures of CoSi. Furthermore, inserting a Cu layer at the Co(Ni, Fe)Si/CoFeB interface results in an increase of the ξSH up to 10.9% for CoSi, 4.0% for Ni0.15Co0.85Si, and 8.3% for Fe0.26Co0.74Si. These enhancements of the ξSH can be attributed to the improvement in the interfacial spin transparency between the Co(Ni, Fe)Si and CoFeB layers.

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Section: Resultsmentioning

confidence: 74%

Elemental Doping and Interface Effects on Spin–Orbit Torques in CoSi‐Based Topological Semimetal Thin Films

Wen

Seki

et al. 2022

Adv Materials Inter

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“…The direction of the loop reverses (changes from clockwise to counter clockwise) when the magnetic field polarity is reversed (see Fig. S2(a) in SI), which is a signature of SOT driven magnetization switching 12 , 16 .…”

Section: Resultsmentioning

confidence: 99%

Spin-torque devices with hard axis initialization as Stochastic Binary Neurons

Ostwal

Debashis

Faria

et al. 2018

Sci Rep

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Employing the probabilistic nature of unstable nano-magnet switching has recently emerged as a path towards unconventional computational systems such as neuromorphic or Bayesian networks. In this letter, we demonstrate proof-of-concept stochastic binary operation using hard axis initialization of nano-magnets and control of their output state probability (activation function) by means of input currents. Our method provides a natural path towards addition of weighted inputs from various sources, mimicking the integration function of neurons. In our experiment, spin orbit torque (SOT) is employed to “drive” nano-magnets with perpendicular magnetic anisotropy (PMA) -to their metastable state, i.e. in-plane hard axis. Next, the probability of relaxing into one magnetization state (+mi) or the other (−mi) is controlled using an Oersted field generated by an electrically isolated current loop, which acts as a “charge” input to the device. The final state of the magnet is read out by the anomalous Hall effect (AHE), demonstrating that the magnetization can be probabilistically manipulated and output through charge currents, closing the loop from charge-to-spin and spin-to-charge conversion. Based on these building blocks, a two-node directed network is successfully demonstrated where the status of the second node is determined by the probabilistic output of the previous node and a weighted connection between them. We have also studied the effects of various magnetic properties, such as magnet size and anisotropic field on the stochastic operation of individual devices through Monte Carlo simulations of Landau Lifshitz Gilbert (LLG) equation. The three-terminal stochastic devices demonstrated here are a critical step towards building energy efficient spin based neural networks and show the potential for a new application space.

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Field-free switching of perpendicular magnetization in a noncollinear antiferromagnetic Mn3Sn/[Pt/Co]4 heterostructure

Lu,

Xu,

Zheng

et al. 2024

Journal of Magnetism and Magnetic Materials

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Spin-orbit torque based magnetization switching in Pt/Cu/[Co/Ni]5 multilayer structures

Cited by 7 publications

References 27 publications

Elemental Doping and Interface Effects on Spin–Orbit Torques in CoSi‐Based Topological Semimetal Thin Films

Elemental Doping and Interface Effects on Spin–Orbit Torques in CoSi‐Based Topological Semimetal Thin Films

Spin-torque devices with hard axis initialization as Stochastic Binary Neurons

Field-free switching of perpendicular magnetization in a noncollinear antiferromagnetic Mn3Sn/[Pt/Co]4 heterostructure

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