As an antisymmetric exchange interaction, the Dzyaloshinskii-Moriya interaction (DMI) favors canted spin alignment and stabilizes chiral spin textures. However, the existing DMI effects, e.g., interfacial DMI, bulk DMI, and interlayer DMI, cannot achieve long-range characteristics and vertical chirality simultaneously, hindering the implementation of three-dimensional (3D) topological magnetic textures. Here, we first achieve a bulk-like interlayer DMI (BIL-DMI) effect in gradient magnetic multilayers by engineering in-plane (IP) and out-of-plane (OOP) symmetry breaking, which presents unprecedented long-range vertical chirality. The direction and magnitude of the BIL-DMI-induced IP/OOP DMI effective fields depend on the DMI gradient, and the OOP effective field exhibits exotically linear dependence on external magnetic fields, distinctly different from the existing saturation behaviors of interlayer DMI. Moreover, a continuum model is built to explain the mechanism of BIL-DMI and quantitatively describe the experimental observations. Based on the BIL-DMI, unique 3D transverse skyrmion/bimeron strings applicable to next-generation magnonic circuits are first stabilized in theory, which is unachievable relying on existing DMI effects. The discovery of BIL-DMI achieves access to a long-range version of IL-DMI through gradient engineering, providing a platform for the investigation and application of 3D topological magnetic textures.

Current-induced spin-orbit torque (SOT) is an effective approach to manipulate magnetic states in spintronic devices. Recent studies show picosecond electrical pulses can induce coherent magnetization switching, reducing switching time from nanosecond scale to picosecond scale. However, it remains unclear whether such ultrafast switching can be achieved in a perpendicular magnetic anisotropy system without an external magnetic field. Here, we demonstrate picosecond all-electrical magnetization switching in a CoTb/Ti/CoFeB/MgO heterostructure, where the in-plane magnetized CoTb layer acts as the SOT source, generating simultaneously in-plane spin current σy and out-of-plane spin current σz. The strong spin-orbit coupling in Tb significantly enhances the SOT efficiency, enabling 16 ps switching with projected 41 fJ/bit consumption in a 100×100 nm² device. Micromagnetic simulations and numerical analysis reveal trade-off between pulse width and energy consumption and identify an optimal σz/σy ratio for energy-efficient switching. Our work promotes the frequency of spintronic devices toward THz regime.

Discovering and effectively leveraging nontrivial magnetic texture in magnetic materials is of great significance for developing next-generation spintronic devices. In this Letter, we demonstrate that solid-state hydrogen gating in rare-earth-transition-metal ferrimagnetic alloys can reversibly create and remove an unconventional magnetic texture called magnetic domains without domain walls, i.e., two adjacent magnetic regions have opposite net magnetization but rare-earth sublattices in these two regions have the same magnetic moment direction. By introducing this nontrivial magnetic texture, spin-orbit torque driven perpendicular magnetization switching is realized in the absence of an external magnetic field. The continuous magnetization reduction tendency of two magnetic sublattices at the boundary between two magnetic domains is responsible for the observed field-free switching phenomenon. Our Letter provides an alternative to leverage spin texture characteristics in information writing and promotes the application of ferrimagnets in spintronic devices.

Transition metal oxides with strong spin-orbit coupling exhibit efficient charge-to-spin interconversion. The modification of crystal structure provides a promising platform for enhancing the spin-orbit torque (SOT) efficiency, which potentially leads to energy-efficient spintronic devices. Here, efficient switching of perpendicular magnetization driven by SOT in CaRuO3 films is reported. By precisely tuning octahedral tilt/rotation, the enhancement of SOT efficiency is achieved, and the corresponding spin Hall conductivity can be increased from the value of 2.48 to 7.56 x (& hbar;/2e) x 104 Omega-1 m-1. The thickness dependence of spin Hall conductivity indicates that SOT originates from the bulk spin Hall effect. Moreover, this large SOT efficiency contributes to the reduction of power consumption in current-induced switching of magnetization. The results provide a route to further enhance the SOT efficiency and verify CaRuO3 as a very promising candidate material for efficient spintronics devices.

In this paper, a three-dimensional all-spin parallel evolutionary computing (ASPEC) device is proposed to realize the evolutionary algorithm in a single device instead of a traditional CMOS circuit. A 3D magnetic tunnel junction (MTJ) array is used to store the genetic information of the whole population. Using the spin transfer torque (STT) effect with spin diffusion mechanism, we realize a parallel computing scheme for chromosome replication, proliferation, crossover, gene mutation, and selection. Getting benefit from the logic-in-memory (LIM) architecture consisting of MTJ arrays, the ASPEC device is not only non-volatile but also avoids memory wall. Our results show that the time complexity of evolutionary algorithms is reduced due to the parallel computing design, and the energy consumption is also significantly cut down owing to non-volatility and its avoidance of Joule heating.

An ultra-fast true random number generator (TRNG) based on ill-posedness nucleation of skyrmion bags (sk-bags) with high topological charge (Q) is proposed and studied via numerical method. Under a local spin-polarized current, the ill-posed dynamics of ferrimagnetic spin texture is induced, resulting in the nucleation of sk-bag with high Q (even vertical bar Q vertical bar >10). Furthermore, in combination with thermal activation, this initially complex phenomenon can be tuned to possess a defined probability distribution of Q. Based on these, we reveal for the first time that the nucleation process of Q, in contrast to the dynamic motion of topological solitons, has the potential to provide an ultra-high true random number generation with a generation rate of 20 Gbit/s, which is the fastest record compared with previous spintronic TRNGs. Finally, we verified the functionality of the device through simulation and demonstrated its advantages in terms of power consumption. Our research provides an additional possibility for developing high-performance TRNG.

Magnetic hopfions are a novel kind of topological solitons existing in three-dimensional (3D) magnets, including chiral magnets, frustrated magnets, and magnetic multilayers. Their rich dynamics is demonstrated to be promising in constructing nonconventional computing architectures. However, the mechanism of a hopfion's inertial motion, which is associated with finding its internal eigenmodes, is still being explored either by rigid-body approximation or by 3D micromagnetic simulation. The first neglects the excitation of internal eigenmodes, while the latter costs substantial computing resources but cannot exhaust the topic. In this paper, a framework based on local eigenmodes is proposed to calculate inertial motion. Utilizing the variational method, the complexity of solving inertial motion is significantly reduced to an eigenproblem with fewer dimensions, thereby fully revealing the modulation mechanism of a hopfion's inertia. We calculate two kinds of inertial motion: translation and rotation, within our framework. This demonstrates that our framework is a comprehensive tool for studying inertial motion. Our research highlights the fascinating dynamics of hopfions and is expected to facilitate the modulation and manipulation of hopfions for wider applications.

The current-induced switching of in-plane exchange bias field (Heb) has many advantages, such as switching without assistance of external magnetic field, excellent immunity to magnetic field, and robust magnetic anisotropy. However, the blocking temperature of the nanoscale antiferromagnet/ferromagnet (AFM/FM) heterostructure is relatively low and susceptible to thermal effects. Therefore, the Joule heating theoretically plays a substantial role in the switching of Heb driven by current, but its underlying mechanism requires further investigation and verification. We prepare a series of Pt/IrMn/Py heterostructures with varying antiferromagnet IrMn thicknesses and systematically investigate the role of thermal effects in current-driven Heb switching. These results demonstrate that under millisecond-level current pulses, Joule heating heats the device above the blocking temperature, leading to the decoupling of exchange coupling at AFM/FM interface. Simultaneously, the Oersted field and spin-orbit torque field generated by the current switch the ferromagnetic moments, and then a new Heb will be induced along the direction of the ferromagnetic moments in the cooling process. Furthermore,in the switching process of Heb, the anisotropic magnetoresistance curve of the AFM/FM heterostructure exhibits a temperature-dependent two-step magnetization reversal phenomenon. Theoretical analysis indicates that this phenomenon arises from the competitive relationship between exchange bias coupling at AFM/FM interface and direct exchange coupling between the ferromagnetic moments. The findings of this study elucidate the crucial role of thermal effects in the current-driven switching of Heb, thereby contributing to the advancement of spintronic devices based on electrically controlled Heb.

The development of spin-based in-memory computing (IMC) depends on the efficient and flexible control of magnetic order. Here, an orthogonal-bulk-spin-orbit-torque (OBSOT) device composed of a gradient ferromagnetic multilayer with an engineered magnetic anisotropy (MA) is proposed to realize field-free and area-selective magnetization switching. Because of the in-plane shape MA, either transverse or longitudinal current can induce field-free BSOT switching. Moreover, these two orthogonal currents can selectively drive magnetization switching of a crossing area. A theoretical model is established to reveal this OBSOT-controlled switching process. Based on a single OBSOT unit, a complete set of Boolean logic operations are experimentally implemented with high switching efficiency, paving the way for dense and efficient all-electrical IMC schemes.

To overcome the interfacial nature of spin‐orbit torque (SOT) in bilayers, novel bulk SOT (BSOT) is widely investigated to implement high‐density and low‐power spintronic devices. However, the underlying mechanism of efficient BSOT switching remains unclear, especially the anomalously enhanced effective spin Hall angle (θSH) with increasing ferromagnet thickness (tFM), due to lacking simple and high‐tunable material systems. Here, a series of Pt/Co multilayers with invariable thickness gradient and varying stacking numbers is designed to systematically explore BSOT origin and enable efficient switching via engineering symmetry breaking. As tFM increases, the critical current density decreases while the switching efficiency and θSH build up. Comparative experiments directly demonstrate that gradient‐induced local spin current is more efficient than that in the bilayer. Moreover, x‐ray absorption spectroscopy (XAS) results reveal that the increasing stacking number can effectively engineer the symmetry breaking at Pt/Co interface to induce strong interfacial spin‐orbit coupling. On this basis, it is concluded that the BSOT effect, as well as the anomalously enhanced switching efficiency, and θSH arises from gradient‐induced bulk and interface symmetry breaking. These findings clarify the underlying mechanism of BSOT, and broaden the scope of material engineering to improve switching efficiency and inspire more memory and computing applications.

Spintronic devices manipulate the electron's spin degree of freedom to provide excellent features such as non-volatility, high speed, high density and low power consumption, which attracted intensive attention in the "post Moore's Law era". Traditional spintronic devices based on ferromagnetic materials are mainly fabricated towards memory applications. Beyond that, our research focuses on the magnetization dynamics in the emerging material systems with antiferromagnetic coupling, including synthetic antiferromagnets (SAFs), ferrimagnets (FIMs) as well as antiferromagnets (AFMs). Based on these, we design spintronic devices that can be used to implement high-performance unconventional computing such as reconfigurable computing in memory (CIM), reservoir computing (RC), and neuromorphic computing. These works demonstrate the potential of spintronic devices for applications in next-generation advanced computing frameworks.

Spintronic devices use spin instead of charge to process information and are widely considered as promising candidates for next-generation electronic devices. In past decades, the main motivation in spintronics has been to discover new mechanisms and novel material systems to improve both device performance and the application prospects of spintronics. Recently, researchers have found that ferrimagnetic materials—in which sublattices are coupled antiferromagnetically—offer an emerging platform for realizing high-density, high-speed, and low-power-consumption memory and logic functions. Within such a ferrimagnetic class, vanishing magnetization and ultrafast magnetic dynamics can be achieved by adjusting chemical composition and temperature, among other parameters. Meanwhile, unlike for antiferromagnets, conventional electrical read–write methods remain suitable for ferrimagnets, which is beneficial for applications. In this review, an abundant class of ferrimagnets including oxides and alloys is surveyed, and unique magnetic dynamics and effective methods for manipulating the magnetic states of ferrimagnets are discussed. Finally, novel storage and computing devices based on ferrimagnets are considered, as there are some challenges to be addressed in future applications of ferrimagnets.

Ferrimagnets are considered an excellent spintronic materialcandidatewhich combines ultrafast magnetic dynamics and straightforward electricaldetectability. However, efficient routes toward magneto-ionic controlof ferrimagnetic order remain elusive. In this study, a solid-stateoxygen gating device was designed to control the magnetic propertiesof the ferrimagnetic CoTb alloy. Experimental results show that applyinga small voltage can irreversibly tune a Tb-dominant device to a stableCo-dominant state and decrease the magnetization compensation temperatureby 130 K. In addition, a reversible voltage control of the magnetizationaxis between out-of-plane and in-plane states is observed, which indicatesthat the migrated oxygen ions can bond to both Tb and Co sublattices.First-principles calculations indicate that voltage can dynamicallycontrol the flow-in and flow-out of oxygen ions that bond to the Cosublattice. Our work provides an effective means to manipulate ferrimagneticorder and contributes to the development of ultra-low-power spintronicdevices.

Spin–orbit torque induced ferromagnetic magnetization switching brought by injecting a charge current into strong spin–orbit-coupling materials is an energy-efficient writing method in emerging magnetic memories and spin logic devices. However, because of the short spin coherence length in ferromagnetic layers, the interfacial effective spin–orbit torque typically leads to high critical current density for switching thick ferromagnet, which goes against low-power and high-density requirements. Here, we experimentally demonstrate efficient bulk spin–orbit torque-driven perpendicular magnetization switching under relatively low critical current density in thick Pt/Co multilayers with gradient-induced symmetry breaking. Through tuning the thickness gradient of Pt, the spin–orbit torque efficiency and switching chirality can be highly controlled, which also indicates that net spin current arises from gradient. Meanwhile, x-ray absorption spectroscopy results reveal that the atomic intermixing can significantly enhance the spin–orbit torque efficiency through improving the strength of spin–orbit-coupling of Pt. We also establish a micromagnetic model by taking both gradient-induced and intermixing-enhanced spin–orbit torque into account to well describe the experimental observations. This work would blaze a promising avenue to develop novel spin–orbit torque devices for high-performance spintronic memory and computation systems.

Spintronic devices are considered as one of the most promising technologies for non-volatile memory and computing. However, two crucial drawbacks, that is, lack of intrinsic multi-level operation and low on/off ratio, greatly hinder their further application for advanced computing concepts, such as deep neural network (DNN) accelerator. In this paper, a spintronic multi-level memory unit with high on/off ratio is proposed by integrating several series-connected magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy (PMA) and a Schottky diode in parallel. Due to the rectification effect on the PMA MTJ, an on/off ratio over 100, two orders of magnitude higher than intrinsic values, is obtained under proper proportion of alternating current and direct current. Multiple resistance states are stably achieved and can be reconfigured by spin transfer torque effect. A computing-in-memory architecture based DNN accelerator for image classification with the experimental parameters of this proposal to evidence its application potential is also evaluated. This work can satisfy the rigorous requirements of DNN for memory unit and promote the development of high-accuracy and robust artificial intelligence applications.

Spin-orbit torque (SOT) is widely considered as an effective route to manipulate magnetic order in spintronic devices. The low power consumption and long endurance demands from future computer architectures urgently require a reduction of the critical SOT switching current density, jsw. However, except for searching for a SOT source with a high-spin Hall angle, few efficient mechanisms to reduce jsw have been proposed. In this work, we achieved an anomalous thermal-assisted (TA) jsw reduction in a Pt/Co/Tb heterostructure through engineering a ferrimagnetic Co/Tb interface. This jsw reduction tendency is demonstrated to be strongly dependent on the thickness of Tb, tTb. When tTb reaches an optimal point (3 nm), a 74 K temperature increase will reduce jsw by more than an order of magnitude (17 times). Comparison experiments and theoretical simulations indicate that this anomalous TA reduction behavior goes beyond the conventional SOT framework and originates from the temperature-sensitive ferrimagnetic interface. We further propose a multifunctional logic-in-memory device, where six different Boolean logic gates can be implemented, to demonstrate the application potential and energy efficiency of this TA SOT switching mechanism. Our work provides an effective alternative to reduce jsw in SOT devices and may inspire future spintronic memory, logic, and high-frequency devices.

目的 了解江苏省扬中市中老年居民糖尿病患病率、知晓率、治疗率和控制率现状及其与社会经济地位(SES)的关系,为提高糖尿病的防控水平提供参考依据.方法 于2018年9月-2019年3月采用多阶段分层整群随机抽样方法在扬中市抽取2 644名≥40岁中老年居民进行问卷调查、体格检查和实验室检测;应用多因素非条件logistic回归分析方法分析扬中市中老年居民糖尿病患病率、知晓率、治疗率和控制率与SES的关系,并计算患病率、知晓率、治疗率和控制率的集中指数(CI)评价健康的公平性.结果 扬中市2591名中老年居民中,患糖尿病者275例,糖尿病患病率为10,6％;275例糖尿病患者中,知晓患病者148例,糖尿病知晓率为53.8％;进行治疗者116例,糖尿病治疗率为42.2％;血糖得到控制者34例,糖尿病控制率为12.4％.在控制了性别、年龄、婚姻状况、居住地、吸烟情况、饮酒情况、锻炼情况、体质指数(BMI)等混杂因素后,多因素非条件logistic回归分析结果显示,初中及以上文化程度中老年居民糖尿病患病率为文盲/半文盲中老年居民的0.486倍(OR= 0.486,95％CI = 0.304～0.778);退休中老年居民糖尿病知晓率和治疗率分别为在职中老年居民的5.026倍(OR = 5.026,95％CI= 1.360～18.568)和2.944倍(OR = 2.944,95％CI= 1.043～8.311);人均年收入中等组和最高组中老年居民糖尿病控制率分别为最低组中老年居民的6.354倍(OR = 6.354,95％CI= 1.228-32.883)和8.404倍(OR = 8.404,95％CI= 1.616～43.700).通过文化程度和职业计算的糖尿病患病率、知晓率、治疗率、控制率的CI值均为负值,分别为-0.029 5、-0.009 3、-0.008 6、-0.013 8和-0.017 4、-0.014 1、-0.011 0、-0.027 5,通过人均年收入计算的糖尿病患病率和知晓率的CI值也为负值(-0.002 6和-0.001 4),但糖尿病治疗率和控制率的CI值为正值(0.020 7和0.077 1).结论 扬中市中老年居民糖尿病患病状况尚可,但知晓率、治疗率和控制率仍处于较低水平;糖尿病患病率、知晓率、治疗率和控制率与SES存在关联,不同SES的居民存在健康不公平性.

Current-induced spin-orbit torques (SOTs) are of interest for fast and energy-efficient manipulation of magnetic order in spintronic devices. To be deterministic, however, switching of perpendicularly magnetized materials by SOT requires a mechanism for in-plane symmetry breaking. Existing methods to do so involve the application of an in-plane bias magnetic field, or incorporation of in-plane structural asymmetry in the device, both of which can be difficult to implement in practical applications. Here, we report bias-field-free SOT switching in a single perpendicular CoTb layer with an engineered vertical composition gradient. The vertical structural inversion asymmetry induces strong intrinsic SOTs and a gradient-driven Dzyaloshinskii-Moriya interaction (g-DMI), which breaks the in-plane symmetry during the switching process. Micromagnetic simulations are in agreement with experimental results, and elucidate the role of g-DMI in the deterministic switching processes. This bias-field-free switching scheme for perpendicular ferrimagnets with g-DMI provides a strategy for efficient and compact SOT device design.

目的 分析台州市某三级综合医院住院病例疾病谱的构成及变化,为卫生资源的合理配置、疾病防治策略的科学制定提供依据.方法 收集某院2011年1月1日-2019年12月31日住院患者信息,包括性别、年龄、入院日期、出院日期、ICD-10编码等,采用描述性研究方法分析某院住院患者疾病谱构成及变化趋势.结果 某院9年内共收治住院患者464400例,且呈逐年上升趋势,其中男性216697例,女性247703例,男女性别比为1∶1.14;年龄集中在60岁及以上年龄组,占比35.88％;疾病谱前10位占住院患者的83.05％;呼吸系统疾病最为常见,构成比为16.08％,多见于儿童和老年人,其次为妊娠分娩和产褥期(12.26％)、循环系统疾病(10.28％);女性最常见的疾病为妊娠分娩和产褥期,共30632例,占女性住院患者的22.98％.结论 住院人次逐年升高,呼吸系统疾病、妊娠分娩和产褥期、循环系统疾病等仍是重点关注的疾病,应结合疾病谱变化及其人群年龄、性别等分布特点进行疾病防治,合理利用卫生资源.

In this letter, we propose a 3D spintronic device stacked by ferrimagnetic (FIM) alloy CoTb layers with a thickness gradient for realizing multi-bit storage and efficient in-memory computing (IMC). Firstly, spin-orbit torque (SOT) induced multi-level magnetization switching of a Pt/CoTb/W/CoTb/Pt stack is experimentally achieved and micromagnetically modeled. Furthermore, a 3D-FIM IMC device with multiple ferrimagnetic layers is constructed and analyzed. Its functionalities of ultra-dense storage and reconfigurable logic are both validated through micromagnetic studies. Due to the ultra-fast dynamics near the compensation point, this 3D-FIM IMC device can operate with ultra-low energy consumption (~18 aJ) and ultra-high speed (~25 ps).