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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. Switching of ferrimagnets by current-induced spin-orbit torque is promising for spintronics, due to their high-speed dynamics and small macroscopic magnetization. Switching of perpendicularly magnetized materials, however, requires a bias field for symmetry breaking. Here, Zheng et al demonstrate field-free current-induced switching of perpendicular ferrimagnets, using a compositional gradient-driven Dzyaloshinskii–Moriya interaction.

The electrical control of the non-trivial topology in Weyl antiferromagnets is of great interest for the development of next-generation spintronic devices. Recent studies suggest that the spin Hall effect can switch the topological antiferromagnetic order. However, the switching efficiency remains relatively low. Here, we demonstrate the effective manipulation of antiferromagnetic order in the Weyl semimetal Mn 3 Sn using orbital torques originating from either metal Mn or oxide CuO x . Although Mn 3 Sn can convert orbital current to spin current on its own, we find that inserting a heavy metal layer, such as Pt, of appropriate thickness can effectively reduce the critical switching current density by one order of magnitude. In addition, we show that the memristor-like switching behaviour of Mn 3 Sn can mimic the potentiation and depression processes of a synapse with high linearity—which may be beneficial for constructing accurate artificial neural networks. Our work paves a way for manipulating the topological antiferromagnetic order and may inspire more high-performance antiferromagnetic functional devices. Electrical control of topological magnets is of great interest for future spintronic applications. Here, the authors demonstrate the effective manipulation of antiferromagnetic order in a Weyl semimetal using orbital torques, with implications for neuromorphic device applications.

In order to advance the silicon integrated circuit technology, researchers have been searching for memory and logic devices with new physical state variables other than charge. Spin logic device that adds one degree of freedom-electron spin to charge has been considered as a promising candidate due to its low power consumption, built-in memory, and high scalability. Here, we demonstrate that a new variable – current direction on the sample can be introduced into the spin logic operation. The current direction of the sample is considered as a vector. For the various input currents along different directions, the direction of vector sum (vector adder) determines the output and therefore can enable complex logic functions. We have realized the basic Boolean logic gates including AND, OR, NAND, NOR, and even complicated IMPLY in a single device and further constructed a full adder with only 2 devices. By increasing the number of degrees of freedom one can reduce overall number of devices required to perform logic operations. Here, Zhao, Zheng, Wang et al demonstrate a device using current direction, a vector property, allowing for the implementation of Boolean logic, including IMPLY in a single device, and further enabling the construction of a full adder with only two devices.

Since the discovery of the giant magnetoresistive (GMR) effect, GMR sensors have gained much attention in last decades due to their high sensitivity, small size, and low cost. The full Wheatstone-bridge-based GMR sensor is most useful in terms of the application point of view. However, its manufacturing process is usually complex. In this paper, we present an efficient and concise approach to fabricate a full Wheatstone-bridge-based angular GMR sensor by depositing one GMR film stack, utilizing simple patterned processes, and a concise post-annealing procedure based on a special layout. The angular GMR sensor is of good linear performance and achieves a sensitivity of 0.112 mV/V/Oe at the annealing temperature of 260 °C in the magnetic field range from −50 to +50 Oe. This work provides a design and method for GMR-sensor manufacturing that is easy for implementation and suitable for mass production.

Racetrack memory (RM) has sparked enormous interest thanks to its outstanding potential for low-power, high-density and high-speed data storage. However, since it requires bi-directional domain wall (DW) shifting process for outputting data, the mainstream stripe-shaped concept certainly suffers from the data overflow issue. This geometrical restriction leads to increasing complexity of peripheral circuits or programming as well as undesirable reliability issue. In this work, we propose and study ring-shaped RM, which is based on an alternative mechanism, spin orbit torque (SOT) driven chiral DW motions. Micromagnetic simulations have been carried out to validate its functionality and exhibit its performance advantages. The current flowing through the heavy metal instead of ferromagnetic layer realizes the “end to end” circulation of storage data, which remains all the data in the device even if they are shifted. It blazes a promising path for application of RM in practical memory and logic.

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. A spintronic multi‐level memory unit (MLMU) is developed by integrating series‐connected magnetic tunnel junctions and a Schottky diode in parallel. Multiple stable resistance states configured by spin transfer torque effect combining with high on/off ratio are achieved. Based on the parameters of MLMU, a computing‐in‐memory based deep neural network accelerator for image classification is evaluated to evidence its application potential.

In this paper, a series of model tests about the trapezoidal filling structures filled with tire reinforced concrete particles has been conducted to study their stability and the ultimate bearing capacity. The effects of the reinforcing tire slices on the global stability and ultimate bearing capacity of the model were investigated, the results show that the tire slices reinforcement can reduce the total settlement of the trapezoidal filling structure, and the ultimate bearing capacity of the reinforced trapezoidal filling structure with tire slices is obviously improved. Among them, the settlements of crushed concrete particles reinforced with bottom layer, top layer, and two layers (both bottom layer and top layer) waste tire slices are 11.5%, 37.7%, and 46.2% less than that of unreinforcement, respectively. Compared with unreinforcement, when the top layer of the model is reinforced with tire slices, the Earth pressure values at the top layer and the bottom layer are reduced by 21.1% and 22.7%, respectively; the Earth pressure values at the top layer and the bottom layer are reduced 6.3% and 14.3%, respectively, when the bottom layer of the model is reinforced with tire slices, and the Earth pressure values at the top layer and the bottom layer are reduced 23.4% and 32.9%, respectively, when the two layers of the model are reinforced with tire slices. The sliding surface of the pure concrete particles filled trapezoidal structure is continuous and runs through the whole trapezoidal filling structure slope; the sliding zone of reinforced trapezoidal filling structure with tire slices decreases with the laying of tire slices.

Older age is a potentially confounding variable in models of telehealth utilization. We compared unified and stratified logistic regression models using data from the 2021 National Health Interview Survey. A total of 27,626 patients were identified, of whom 38.9% had utilized telehealth. Unified and stratified modeling showed a number of important differences in their quantitative estimates, especially for gender, Hispanic ethnicity, heart disease, COPD, food allergies, high cholesterol, weak or failing kidneys, liver conditions, difficulty with self-care, the use of mobility equipment, health problems that limit the ability to work, problems paying bills, and filling a recent prescription. Telehealth utilization odds ratios differ meaningfully between younger and older patients in stratified modeling. Traditional statistical adjustments in logistic regression may not sufficiently account for the confounding influence of older age in models of telehealth utilization. Stratified modeling by age may be more effective in obtaining clinical inferences.

In order to study the mechanical properties of tire slices reinforced crushed concrete particles, a series of shear tests were carried out under the conditions of different vertical loads, different tire volume contents, and different shear rates. The test results show that the addition of tire slices can increase the internal friction angle and cohesion of concrete particles, therefore increase the shear strength of crushed concrete particles. The peak shear stress increases with the increase of vertical load. However, with the increase of the tire volume content, the reinforcement effect of the tire slices first increases and then decreases, and the effect is best when the tire volume content is 4%. Under the vertical load of 60 kPa, the reinforcement effect of 4% tire volume content is the best, and the peak shear stress increases by 46.53%. Additionally, the shear rate has a little effect on the peak shear stress. The larger the shear rate is, the smaller the shear displacement is and the faster the shear strength decreases. The smaller the shear rate is, the more gently the shear strength decreases.

Orbital angular momentum has recently been demonstrated as a promising approach to manipulate magnetic order in spintronic devices with high efficiency. While the generation of orbital angular momentum is generally attributed to electron orbital hopping and hybridization, its experimental manifestations have often been discussed in an isotropic manner. In crystalline systems, however, orbital hybridization is inherently constrained by crystal symmetry, suggesting that symmetry can play a decisive role in shaping the anisotropy of orbital angular momentum-related responses. In this work, we report a crystal-symmetry-dependent orbital Rashba-Edelstein effect in a distinct epitaxially grown CuO thin film with four-fold crystal symmetry. A crystal-symmetry-dependent sign change of spin torque efficiency is observed in the CuO/ferromagnetic heterostructures, verified by second harmonic Hall measurement and current-induced perpendicular magnetization switching. The experimental results, together with the first-principles calculation, indicate the existence of a strong four-fold anisotropy of orbital Rashba-Edelstein effect in crystalline CuO, which is a direct manifestation of the crystal symmetry's impact on the anisotropy of orbital angular momentum-related response. These findings establish crystal symmetry as a key factor governing the anisotropy of orbital angular momentum-related phenomena and provide a symmetry-based framework for orbitronic functionalities in advanced spintronic devices.