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1.
The recent discovery of spin-orbit torques (SOTs) within magnetic single-layers has attracted attention. However, it remains elusive as to how to understand and how to tune the SOTs. Here, utilizing the single layers of chemically disordered FexPt1-x, the mechanism of the “unexpected” bulk SOTs is unveiled by studying their dependence on the introduction of a controlled vertical composition gradient and temperature. The bulk dampinglike SOT is found to arise from an imbalanced internal spin current that is transversely polarized and independent of the magnetization orientation. The torque can be strong only in the presence of a vertical composition gradient. The SOT efficiency per electric field is insensitive to temperature but changes sign upon reversal of the orientation of the composition gradient, which is analog to the strain behaviors. These characteristics suggest that the imbalanced internal spin current originates from a bulk spin Hall effect and that the associated inversion asymmetry that allows for a non-zero net torque is most likely a strain non-uniformity induced by the composition gradient. The fieldlike SOT is a relatively small bulk effect compared to the dampinglike SOT. This study points to the possibility of developing low-power single-layer SOT devices by strain engineering. 相似文献
2.
The manipulation of magnetization through optically generated ultrafast spin currents is a fascinating area that needs a thorough understanding for its potential future applications. In this work, a comprehensive investigation of helicity-driven optical spin-orbit torque in heavy metal/ferromagnetic metal heterostructures is presented, specifically cobalt capped with gold or platinum, subject to laser pumping at different wavelengths. The results demonstrate up to tenfold enhancement in optical spin-orbit torque quantum efficiency for gold compared to platinum of the same thickness when pumped with a visible laser. Additionally, the study provides the first experimental analysis of the photon energy dependence of optical spin-orbit torque and derives the optical spin orientation spectra for both gold/cobalt and platinum/cobalt heterostructures. A key insight gained from the study is the impact of photon energy-dependent spin transport in the system, which suggests the use of a high photon energy pump for efficient spin transport. These findings highlight the potential of spin current generation and manipulation in gold/ferromagnet heterostructures for a wide range of applications such as all-optical magnetization switching, spin-wave generation and control, and spintronic terahertz emission. 相似文献
3.
Haodong Fan Menghao Jin Yongming Luo Hongxin Yang Birui Wu Zhongshu Feng Yanshan Zhuang Ziji Shao Changqiu Yu Hai Li Jiahong Wen Ningning Wang Bo Liu Wenjun Li Tiejun Zhou 《Advanced functional materials》2023,33(16):2211953
Deterministic switching of perpendicularly magnetized synthetic antiferromagnets using spin-orbit torque (SOT) usually requires an in-plane auxiliary magnetic field, which limits its practical applications. Here, an exchange field gradient is introduced into perpendicularly magnetized synthetic ferro- and antiferromagnets (SFs and SAFs) through the insertion of a slightly wedged Ru between two thin ferromagnetic layers, which induces field-free switching of perpendicular SFs and SAFs with a switching ratio up to 81% regardless of the nature of the coupling. Temperature-dependent measurement shows a robust field-free switching even at low temperature. The experimental results show that the field-free switching ratio and the effective SOT field are directly related to the exchange field gradient. The theoretical model and numerical simulation indicate that the dynamic noncollinear spin textures induced by the exchange field gradient lead to the field-free switching, while the sign of the exchange field gradient determines the field-free switching polarity. It is further revealed that the SOT efficiency is positively correlated with the antiferromagnetic exchange field for both Ru wedged and non-wedged samples. These results provide a new avenue for simultaneously achieving field-free switching and high SOT efficiency of perpendicularly magnetized SAFs for highly stable, high-density, low-stray-field, and low-power magnetic memory devices. 相似文献
4.
Martín Testa‐Anta Beatriz Rivas‐Murias Vernica Salgueirio 《Advanced functional materials》2019,29(36)
A combined Raman spectroscopy and magnetometry study of CoFe2O4–Cr2O3 nanocomposites demonstrates the presence of spin–phonon interactions and exchange bias at the interface between the ferrimagnetic CoFe2O4 and the antiferromagnetic and magnetoelectric Cr2O3 phases. The pinned layer of uncompensated spins at the surface of the chromium oxide nanocrystals provides a source of unidirectional anisotropy and changes the sign of the exchange bias when transitioning from a canted to a frustrated situation, that is, as increasing the percentage of CoFe2O4 or decreasing the percentage of Cr2O3 in the composites. This assessment of the distinctive interfaces attained in the final oxide heterostructures offers a prospective route for hybrid materials which uphold a magnetoelectric effect. 相似文献
5.
Yuhang Song Zhiming Dai Long Liu Jinxiang Wu Tingting Li Xiaotian Zhao Wei Liu Zhidong Zhang 《Advanced Electronic Materials》2023,9(1):2200987
Field-free switching is a critical issue for spin-orbit torque-induced magnetic random-access memory (SOT-MRAM) with perpendicular magnetic anisotropic (PMA) towards application. If only the spin-polarized electrons along the y-direction (σy) are used, deterministic switching cannot be achieved, as the electron polarization direction and easy magnetization direction are orthogonal. In this work, z-direction polarized electrons (σz) produced by the spin Hall effect are utilized to provide the switching direction and σy provides the propulsion of magnetic reorientation. With the cooperation of σy and σz by the spin Hall effect, field-free switching is achieved. To combine with magnetic tunnel junction (MTJ), a model is proposed, in which heavy metals providing σz are deposited on MTJ with asymmetric writing line widths. This model retains the characteristics of read-write separation and realizes deterministic switching based on SOT. 相似文献
6.
《Advanced Electronic Materials》2017,3(3)
Spin logic devices, due to their programmability and nonvolatility, are deemed as an ideal building block for the next generation of electronics. Though several types of spin logic based on domain wall motion, spin‐field‐effect transistor and automata made of magnetic nanoparticles have been proposed, an architecture with scalability, energy efficiency and compatibility with current complementary metal‐oxide‐semiconductor technology is still in urgent demand. Here, it is experimentally demonstrated that the spin Hall effect in magnetic films with perpendicular anisotropy can be utilized to construct such a spin logic device. Five commonly used logic gates with nonvolatility in a single device are realized. This demonstration could pave the way towards application of spintronics in logic circuits as well as the memory industry in the near future and could even give birth to logic‐in‐memory computing architectures. 相似文献
7.
Jijun Yun Qiaoning Bai Ze Yan Meixia Chang Jian Mao Yalu Zuo Dezheng Yang Li Xi Desheng Xue 《Advanced functional materials》2020,30(15)
Multilevel remanence states have potential applications in ultra‐high‐density storage and neuromorphic computing. Continuous tailoring of the multilevel remanence states by spin‐orbit torque (SOT) is reported in perpendicularly magnetized Pt/Co/IrMn heterostructures. Double‐biased hysteresis loops with only one remanence state can be tuned from the positively or negatively single‐biased loops by SOT controlled sign of the exchange‐bias field. The remanence states associated with the heights of the sub‐loops are continually changed by tuning the ratio of the positively and negatively oriented ferromagnetic domains. The multilevel storage cells are demonstrated by reading the remanent Hall resistance through changing the sign and/or the magnitude of current pulse. The synaptic plasticity behaviors for neuromorphic computing are also simulated by varying the remanent Hall resistance under the consecutive current pulses. This work demonstrates that SOT is an effective method to tailor the remanence states in the double‐biased heavy metal/ferromagnetic/antiferromagnetic system. The multilevel‐stable remanence states driven by SOT show potential applications in future multilevel memories and neuromorphic computing devices. 相似文献
8.
Zelalem Abebe Bekele Runze Li Yucai Li Yi Cao Xionghua Liu Kaiyou Wang 《Advanced Electronic Materials》2021,7(12):2100528
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. 相似文献
9.
Gerard Joseph Lim Daniel Chua Weiliang Gan Chandrasekhar Murapaka Wen Siang Lew 《Advanced Electronic Materials》2020,6(4)
Driven by the need to address both the von Neumann bottleneck and scaling limits predicted by Moore's law, spintronic devices have been shown to be strong contenders for logic‐in‐memory applications. While several field‐free spin–orbit torque (SOT)‐driven logic devices have been proposed, their operation typically requires additional initialization or reset pulses, the exchange‐coupled canted spins reduce both anomalous Hall sign‐to‐noise ratio as well as thermal stability of the ferromagnetic layer, and device‐to‐device variation in exchange coupling strength is expected. A reconfigurable SOT‐driven logic device using a double Hall cross structure with an integrated bias field line for the generation of a local bias field is experimentally demonstrated. The on‐chip bipolar bias field can be toggled to flip the SOT‐induced switching chirality, and to assist with deterministic SOT magnetization switching, thereby enabling on‐the‐fly reconfigurability of the logic device to function as one of the several possible logic gates, e.g., AND, NOR, XNOR, XOR, NIMP, and converse NIMP. It is then shown through compact‐modeling and circuit simulation that the applications of such reconfigurable logic devices can be further expanded to build half‐adders. 相似文献
10.
Chenbo Zhao Laichuan Shen Baoshan Cui Bin He Chuangwen Wu Jiahui Li Yao Guang Zhuyang Nie Xiao Zheng Gen Yin Ka Shen Hao Wang Shiheng Liang Yan Zhou Xiufeng Han Guoqiang Yu 《Advanced functional materials》2024,34(42):2405296
Magnetic skyrmions are topologically protected spin textures with nanoscale dimensions. They hold great promises as the building blocks for new generations of racetrack memories and computing devices due to their prominent properties. However, skyrmionic devices fabricated within the framework of conventional lithography usually suffer from magnetic disorders at material boundaries where spin disorders can easily pin and destroy magnetic skyrmions. In the present work, a new paradigm is demonstrated that enables the precise patterning and control of micro-scale skyrmion bubble devices using the domain walls rather than the physical boundaries of the material. Such a paradigm patterns the background magnetic domain to stage the skyrmion motion, which is precise, reconfigurable, nondestructive, and can resolve the conventional issues introduced by disorders. This paradigm is demonstrated by implementing a skyrmion diode using a precisely patterned asymmetric racetrack defined by magnetic domains. The interaction between a moving skyrmion and the staging domain walls is well understood by both skyrmion motion experiments and micromagnetic simulations. Such a new paradigm serves as a crucial foundation for device applications of magnetic skyrmions in general. 相似文献
11.
James Lourembam Lisen Huang Bingjin Chen Jinjun Qiu Hong Jing Chung Sherry Lee Koon Yap Qi Jia Yap Seng Kai Wong Sze Ter Lim 《Advanced Electronic Materials》2021,7(4):2001133
Multi-state spin-orbit torque (SOT) switching, particularly in magnetic tunnel junction (MTJ) geometry, is promising hardware for artificial intelligence due to its potential to form artificial neurons and to increase storage density per bit. Here, multi-state switching is demonstrated in Pt/Co40Fe40B20/MgO-based elliptical MTJ, fabricated on a 200 mm wafer platform, using nanosecond spin-orbit torque pulses. Multi-state switching is achieved using MTJs composed of a single ferromagnetic storage layer and without resorting to any domain-wall pinning step. The genesis of the multi-states, rather than the expected bistable states in MTJs, come from the formation and stabilization of metastable domains by the voltage pulse. The persistence and the probability of the mid-states are investigated by two different spin-orbit torque pulse sequences. Additionally, it is reported that size (>domain-wall width), exchange constant (<20 × 10−12 J m-1), current density amplitude (≈threshold values), and pulse sequence are important considerations for realizing multi-state SOT MTJs. These industry-grade MTJs can be leveraged to accelerate the development of spintronics-based neuromorphic devices. 相似文献
12.
We theoretically predict the appearance of a persistent charge current in a Rashba ring with a normal and a ferromagnetic lead under no external bias. This charge current is the result of the breaking of the time inversion symmetry in the original persistent pure spin current induced by the Rashba spin-orbit coupling (RSOC) in the ring due to the existence of the ferromagnetic lead. With the Keldysh Green''s function technique, we find that not only the magnitude and sign but also the spin polarization of the generated charge current is determined by the system parameters such as the magnetization direction of the ferromagnetic lead, the tunneling coefficient, the strength of the RSOC and the exchange energy of the ferromagnetic lead, which are all tunable in experiments, that is, a controllable persistent spin-polarized charge current can be obtained in such a device. 相似文献
13.
Hongyu An Satoshi Haku Yuito Kageyama Akira Musha Yuya Tazaki Kazuya Ando 《Advanced functional materials》2020,30(30)
External manipulation of spin‐orbit torques (SOTs) promises not only energy‐efficient spin‐orbitronic devices but also versatile applications of spin‐based technologies in diverse fields. However, the external electric‐field control, widely used in semiconductor spintronics, is known to be ineffective in conventional metallic spin‐orbitronic devices due to the very short screening length. Here, an alternative approach to control the SOTs by using gases is shown. It is demonstrated that the spin‐torque generation efficiency of a Pd/Ni81Fe19 bilayer can be reversibly manipulated by the absorption and desorption of H2 gas, which appears concomitantly with the change of the electrical resistance. It is found that compared with the change of the Pd resistance induced by the H2 absorption, the change of the spin‐torque generation efficiency is almost an order of magnitude larger. This result provides a new method to externally manipulate the SOTs and paves a way for developing more sensitive hydrogen sensors based on the spin‐orbitronic technology. 相似文献
14.
Yinuo Yan Caihua Wan Xiangjun Zhou Guoyi Shi Bin Cui Jiahao Han Yihong Fan Xiufeng Han Kang L. Wang Feng Pan Cheng Song 《Advanced Electronic Materials》2016,2(10)
Electrical control of current‐induced spin–orbit effects in magnets is supposed to reduce the power consumption in high‐density memories to the utmost extent, but the efficient control in metallic magnets at a practical temperature remains elusive. Here, the electrical manipulation of spin–orbit torque is investigated in perpendicularly magnetized Pt/Co/HfOx heterostructures in a nonvolatile manner using an ionic liquid gate. The switching current of magnetization can be reversibly tuned by a factor of two within a small gate voltage range of 1.5 V. The modulation of effective spin Hall angle and the corresponding damping‐like torque mainly accounts for the strong electrical manipulation of switching current. Besides the fundamental significance, the findings here may advance the process toward the compatible memory and logic devices driven by dual electrical means, the electric field, and current. 相似文献
15.
Qikun Huang Yanan Dong Xiaonan Zhao Jing Wang Yanxue Chen Lihui Bai Ying Dai Youyong Dai Shishen Yan Yufeng Tian 《Advanced Electronic Materials》2020,6(3)
Voltage‐driven oxygen ion migration in ferromagnetic metal/oxide heterostructures offers a highly effective means to tailor emergent interfacial functionalities. In heterojunctions with a core structure of Pt/Co/CoO/TiO2 (TaOx), it is demonstrated that exchange coupling of magnetic moments across the Co/CoO interface provides an extra source to stabilize the perpendicular magnetic anisotropy (PMA). Moreover, the strength of this interfacial coupling can be reversibly controlled through voltage‐driven oxygen ion migration at the Co/CoO interface, resulting in electrical‐field‐controllable PMA. In combination with the spin current generated from Pt, it is revealed that the spin‐orbit torque (SOT) switching of the perpendicular magnetization of Co can be turned ON/OFF by electrical field. Tunable PMA and SOT switching makes heavy metal/ferromagnetic metal/antiferromagnetic oxide heterojunctions a promising candidate to future voltage‐controlled, ultralow‐power, and high‐density spintronics devices. 相似文献
16.
Changsoo Kim Byong Sun Chun Jungbum Yoon Dongseuk Kim Yong Jin Kim In Ho Cha Gyu Won Kim Dae Hyun Kim Kyoung‐Woong Moon Young Keun Kim Chanyong Hwang 《Advanced Electronic Materials》2020,6(2)
The switching of magnetization via spin‐orbit torque has attracted much attention because of its fast switching and low power consumption. Numerous studies have focused on increasing the conversion efficiency from charge to spin current and out‐of‐plane magnetization cases. Recently, there have been reports on the fast and deterministic switching of in‐plane magnetization devices. It is reported that an in‐plane spin‐orbit torque (SOT) device can archive the oscillation, precession, and direct switching by a combination of torques—controlling the thickness of the ferromagnet and normal metal. With proper layer thicknesses, the device can show the three dynamics listed above at each current density in a macro spin simulation. Based on an understanding of the role of torque‐driving magnetization dynamics, a dynamic map of an in‐plane SOT device depending on torque efficiency and current density is shown. 相似文献
17.
18.
Dequan Meng Shiwei Chen Chuantong Ren Jiaxu Li Guibin Lan Chaozhong Li Yong Liu Yurong Su Guoqiang Yu Guozhi Chai Rui Xiong Weisheng Zhao Guang Yang Shiheng Liang 《Advanced Electronic Materials》2024,10(4):2300665
The utilization of novel noncollinear antiferromagnetic materials holds great promise for the development of energy-efficient spintronic devices. However, only a few studies have reported on the all-electrical control of perpendicular magnetization switching using noncollinear antiferromagnets as the spin source, and the underlying mechanism behind the unconventional spin-orbit torque (SOT) is still a topic of debate. In this work, deterministic perpendicular magnetization switching in Mn3Sn/CoTb bilayers is successfully achieved. Compared to the control samples with heavy metal as the spin source, the critical switching current density is over one order of magnitude reduced, indicating an enhanced efficiency of the out-of-plane charge-to-spin conversion in the textured Mn3Sn films. The influence of film thickness and growth temperature on the efficiency of different spin polarizations suggests potential roles of crystal quality and spin texture in spin diffusion with different spin polarization directions. These findings provide valuable insights into the crystal structure, spin-orbit torque effects, and charge-to-spin conversion in Mn3Sn films, highlighting the importance of understanding interface and bulk contributions in antiferromagnetic spin transport phenomena. 相似文献
19.
Uday Singh W. Echtenkamp M. Street Ch. Binek S. Adenwalla 《Advanced functional materials》2016,26(41):7470-7478
The writing of micrometer‐scaled exchange bias domains by local, laser heating of a thin‐film heterostructure consisting of a perpendicular anisotropic ferromagnetic Co/Pd multilayer and a (0001) oriented film of the magnetoelectric antiferromagnet Cr2O3 (chromia) is reported. Exchange coupling between chromia's boundary magnetization and the ferromagnet leads to perpendicular exchange bias. Focused scanning magneto‐optical Kerr measurements are used to measure local hysteresis loops and create a map of the exchange bias distribution as a function of the local boundary magnetization imprinted in the antiferromagnetic pinning layer on field cooling. The robust boundary magnetization of the Cr2O3 fundamentally alters the exchange bias mechanism, enabling the writing of micrometer‐scaled regions of oppositely directed exchange bias using a focused laser beam. 相似文献
20.
Heng-An Zhou Jiahao Liu Zidong Wang Qihan Zhang Teng Xu Yiqing Dong Le Zhao Soong-Geun Je Mi-Young Im Kun Xu Jing Zhu Wanjun Jiang 《Advanced functional materials》2021,31(46):2104426
Interfacially asymmetric magnetic multilayers made of heavy metal/ferromagnet have attracted considerable attention in the spintronics community for accommodating spin-orbit torques (SOTs) and meanwhile for hosting chiral spin textures. In these multilayers, the accompanied interfacial Dzyaloshinskii–Moriya interaction (iDMI) permits the formation of Néel-type spin textures. While significant progresses have been made in Co, CoFeB, Co2FeAl, CoFeGd based multilayers, it would be intriguing to identify new magnetic multilayers that could enable spin-torque controllability and meanwhile host nanoscale skyrmions. In this report, first, thin films made of permanent magnet SmCo5 with perpendicular magnetic anisotropy are synthesized, in which the deterministic SOT switching, enabled by the spin Hall effect, in Pt/SmCo5/Ta trilayer is demonstrated. Further, the stabilization of room-temperature skyrmions with diameters ≈100 nm in [Pt/SmCo5/Ta]15, together with a skyrmionium-like spin texture in [Pt/SmCo5/Ir]15 multilayers is shown. Based on the material specific parameters, micromagnetic simulations are also carried out. The results confirm the presence of chiral spin textures in this new material family. Through interfacial engineering, the results thus demonstrate that rare earth permanent magnets could be a new platform for studying interfacial chiral spintronics. 相似文献