Field-Free Magnetization Switching Induced by Bulk Spin–Orbit Torque in a (111)-Oriented CoPt Single Layer with In-Plane Remanent Magnetization

Li, Zhi; Zhang, Kun; Shen, Lvkang; Xie, Xuejian; Chen, Weibin; Zhou, Zitong; Lu, Lu; Liu, Ming; Shen, Yan; Zhao, Wei; Leng, Qunwen

doi:10.1021/acsaelm.2c00672

Cited by 15 publications

(16 citation statements)

References 47 publications

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“…In the early 1990s, epitaxial thin films (about 50 nm thick) of FePt (001) with perpendicular magnetic anisotropy were obtained [14]. In numerous cases, FePt films were deposited on a conventional MgO substrate [14,21,24,28,29,31], quite often on silver [19], oxidized silicon [18,25,32], and other glassy substrates [33,34]. Experimentally obtained L1 0 FePt thin films are usually not continuous but granular, which provides an additional degree of freedom that can be controlled to improve the desired properties and achieve dedicated patterned surface films [20].…”

Section: Introductionmentioning

confidence: 99%

“…Since then, several other ways of achieving a film with tilted magnetization have been considered, such as ferromagnetic coupling of a tilted top Co layer with an in-plane magnetized bottom Co layer [38]. Much attention has been paid in particular to L1 0 FePt and CoPt films [32,39], which can be deposited on the substrate in such a way that the unique tetragonal axis is strongly deviated from the plane of the film, as in the case of the growth of the FePt films with a (111) surface [33,34,40,41]. The L1 0 FePt (111) films in the aforementioned experiments have a thickness of 20 to 60 nm.…”

Section: Introductionmentioning

confidence: 99%

“…The L1 0 FePt (111) films in the aforementioned experiments have a thickness of 20 to 60 nm. In contrast, the fabricated (111)oriented CoPt single layer had a thickness of 5 nm [32]. The L1 0 FePt (111) films were deposited on oxidized Si (001) and (100) surfaces [25,42], Si (100) covered with 5 nm MgO [15], Ta [40], and metallic glasses such as CoFeTaB [33] and FeHfNbYB [34].…”

Section: Introductionmentioning

confidence: 99%

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L1$_0$ FePt thin films with tilted and in-plane magnetic anisotropy: first-principles study

Marciniak¹,

Werwiński²

2023

Preprint

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Ultrathin L10 FePt films with different c-axis orientations relative to the film plane are promising candidates for data storage materials. In this work, within the framework of density functional theory, we calculated the magnetic properties of ultrathin L10 FePt (111) and (010) films with thicknesses ranging from 4 to 16 atomic monolayers (from about 0.8 to 3.5 nm). The highest average magnetic moments are observed for the thinnest films considered, and with increasing film thickness, the values converge towards the magnetic moment for bulk. The observed increase comes mainly from enhanced moments in the two atomic monolayers closest to the surface of the films. The easy axis of magnetization of (111) films prefers an alignment close to the tetragonal axis, an example of tilted magnetic anisotropy. The 6-monolayer ( 111) film (about 1.3 nm thick) inclines the easy axis of magnetization of about 45°to the film plane, which can find use in applications. The (010) films show an in-plane easy magnetization axis in a unique L10 tetragonal direction. This is an unusual type of in-plane anisotropy, as the particular direction preference is very strong. The computational results encourage further experimental studies of L10 systems with tilted and in-plane fixed magnetic anisotropy.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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L1$_0$ FePt thin films with tilted and in-plane magnetic anisotropy: first-principles study

Marciniak¹,

Werwiński²

2023

Preprint

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“…However, the switching performance is still need to be further improved in such single FM systems. However, by using conventional eld-free switching strategies, such as interlayer exchange coupling 15 , in-plane remanent magnetization 22 , or crystal-symmetry design 21 , the switching of the CoPt layer are often partial, the switching ratio is normally below 70%. As the switching directly determine the device performance in SOT-MRAM application 23,24 , full-scale (100% switching ratio) and reliable switching of the CoPt single layer is highly demanded, while has not been reported to the best of our knowledge.…”

Section: Introductionmentioning

confidence: 99%

Full-scale field-free spin-orbit switching of the CoPt layer grown on vicinal substrates

Che

Luo

Liang

et al. 2023

Preprint

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A simple, reliable and field-free spin orbit torque (SOT)-induced magnetization switching is a key ingredient for the development of the electrical controllable spintronic devices. Recently, the SOT induced deterministic switching of the CoPt single layer has attracts a lot of interests, as it could simplifies the structure and add new flexibility in the design of SOT devices, compared with the Ferromagnet/Heavy metal bilayer counterparts. Unfortunately, under the field-free switching strategies used nowadays, the switching of the CoPt layer is often partial, which sets a major obstacle for the practical applications. In this study, by growing the CoPt on vicinal substrates, we could achieve the full-scale (100% switching ratio) field-free switching of the CoPt layer. We demonstrate that when grown on vicinal substrates, the magnetic easy axis of the CoPt could be tilted from the normal direction of the film plane; the strength of Dzyaloshinskii–Moriya interaction (DMI) would be also be tuned as well. Micromagnetic simulation further reveal that the field-free switching stems from tilted magnetic anisotropy induced by the vicinal substrate, while the enhancement of DMI help reducing the critical switching current. In addition, we also found that the vicinal substrates could also enhance the SOT efficiency. With such simplestructure, full-scale switching, tunable DMI and SOT efficiency, our results provide a new knob for the design SOT-MRAM and future spintronic devices.

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“…Recently, the field-free SOT switching based on the CoPt single-layer structure has been extensively studied. For example, Li implemented field-free magnetization switching induced by bulk SOT in a single (111)-oriented CoPt magnetic layer deposited on the Si/SiO 2 substrates with in-plane remanent magnetization, and Liu studied the CoPt (111) thin films with different compositions grown by SrTiO 3 (111) epitaxial and one composition of CoPt grown on MgO (111) . Actually, the different mismatch strains between the film and substrate would induce different perpendicular anisotropy and chemical ordering, thus causing the discrepancy of SOT properties.…”

Section: Introductionmentioning

confidence: 99%

Field-Free Magnetization Switching in A1 CoPt Single-Layer Nanostructures for Neuromorphic Computing

Yang

Zuo

Tao

et al. 2023

ACS Appl. Nano Mater.

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Current-induced field-free magnetization switching in single-layer films has been widely investigated for the application of spin−orbit torque (SOT) drivers in low-power, high-density, and nano-sized memory. In this paper, we report field-free SOT switching with threefold angle dependence in A1 disordered singlelayer CoPt using the MgO (111) substrate. It is found that the magnetization could not switch in the absence of an external inplane magnetic field when the current was flowing in the direction of the mirror symmetry high-symmetry axis ([11−2]). While along the direction of the low-symmetry axis ([1−10]) which destroyed the mirror symmetry to the greatest extent, field-free switching could be performed, and the switching ratio was up to 30%. This was mainly attributed to the composition gradient-induced in-plane inversion asymmetry and the low symmetry at the interface of Co/Pt broken out-of-plane inversion. Furthermore, CoPt devices with nanoscale thickness exhibited stable multistate magnetic switching behavior without an external magnetic field, and simultaneously nonlinear synaptic characteristics were obtained. A neural network was established, in which the synaptic weights between the hidden layer and the output layer are updated by using the resistance state of SOT synaptic devices, and the network could achieve about 90.54% recognition accuracy when applied to MNIST's handwritten digital dataset. This work confirmed that a field-free SOT switch could be realized in single-layer CoPt, which provided theoretical guidance and data support for spin devices.

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Field-Free Magnetization Switching Induced by Bulk Spin–Orbit Torque in a (111)-Oriented CoPt Single Layer with In-Plane Remanent Magnetization

Cited by 15 publications

References 47 publications

L1$_0$ FePt thin films with tilted and in-plane magnetic anisotropy: first-principles study

L1$_0$ FePt thin films with tilted and in-plane magnetic anisotropy: first-principles study

Full-scale field-free spin-orbit switching of the CoPt layer grown on vicinal substrates

Field-Free Magnetization Switching in A1 CoPt Single-Layer Nanostructures for Neuromorphic Computing

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