Two-dimensional ferromagnetic materials hold great promise for advancing low-power, high-integrated spintronic devices due to their atomic flat surfaces and versatile interfacial modulation. However, achieving a combination of room-temperature, field-free spin-orbit torque switching with tunable polarity in wafer-scale vdW heterostructures remains a significant challenge. Here, we demonstrate polarity-tunable, field-free spin-orbit torque switching in an all-vdW Bi2Te3/Fe4GeTe2 heterostructure, grown by molecular beam epitaxy. Interfacial coupling induces perpendicular magnetic anisotropy in Bi2Te3/Fe4GeTe2 interface, while the rest in-plane magnetic anisotropy component of Fe4GeTe2 breaks the inversion symmetry, enabling field-free switching. By modulating the direction of in-plane component, magnetic switching with different polarity could be achieved at low current density (~1.55×106 A/cm2). This allows for 16 reconfigurable Boolean logic functions in a single device, paving a pathway for energy-efficient 2D spintronic memory and logic systems. Our findings highlight the potential of all-vdW spin-orbit torque devices to revolutionize spintronics with scalable, room-temperature electronic control.

The discovery of intrinsic two-dimensional ferromagnetic materials (2D FMs) with long-range magnetic order has revolutionized spintronics field, offering unprecedented opportunities for developing ultra-compact, low-power, and non-volatile devices. This comprehensive review surveys the latest advancements in this rapidly evolving field. In this work, we first outline the fundamental concepts and unique physical properties of diverse 2D FMs, categorized into transition metal halides, dichalcogenides, and ternary compounds, highlighting representative materials like CrI3, CrTe2, Fe3GeTe2, and Fe3GaTe2 that exhibit magnetism down to the monolayer limit and, crucially, above room temperature. Next, we discuss various synthesis techniques for obtaining high-quality 2D FMs, such as mechanical exfoliation, molecular beam epitaxy (MBE), and chemical vapor deposition (CVD). Subsequently, we delve into critical strategies for manipulating their magnetic characteristics, including strain engineering, electric field modulation, interface effects (proximity, stacking, twist angle), and elemental doping, enabling precise control over Curie temperature, magnetic anisotropy, and switching behavior. The core of the review focuses on key spintronic phenomena leveraged in 2D FMs, such as efficient spin-orbit torque (SOT) switching, exchange bias effects, and the stabilization of magnetic skyrmions, emphasizing their underlying mechanisms and tunability. On this basis, we extensively examine the application of 2D FMs in pioneering spintronic devices, including spin valves and magnetic tunnel junctions (MTJs) demonstrating significant magnetoresistance at room temperature, as well as other emerging devices like spin transistors, neuromorphic components, and terahertz emitters. Finally, we discuss the current challenges and provide perspectives on future research directions aimed at addressing obstacles in material synthesis, stability, and integration. This review underscores the transformative potential of 2D FMs in reshaping information storage, processing, and sensing technologies at the atomic scale.

To enhance the sensitivity of optical fiber magnetic sensors, an optimization strategy based on the synergistic regulation of bias magnetic field and pre-compressive stress was proposed in this study. Firstly, a multi-physics coupling model of "magnetic-mechanical-optical" was established based on magnetostrictive model and the sensing principle of fiber Bragg gratings (FBGs). Then, a sensitivity optimization model considering both bias magnetic field and pre-compressive stress was derived to reveal their underlying tuning mechanisms. Subsequently, the details of the sensor structure incorporating pre-compressive stress and bias magnetic field as well as the corresponding experimental setup were provided. Finally, the individual and combined effects of precompressive stress and bias magnetic field on sensor sensitivity were experimentally evaluated. Under the optimal combination of pre-compressive stress and bias magnetic field, the sensitivity reached 17.31 pm/mT, which was 117 % higher than that of without optimization. This study confirmed the effectiveness of the proposed synergistic optimization strategy and provided a novel approach for further enhancing the performance of optical fiber magnetic sensors.

Inverted hysteresis loops (IHLs) exhibiting negative coercivity and remanence represent a counterintuitive phenomenon in magnetic systems, with origins remaining elusive. Here, we address this long-standing paradox through combined experimental and theoretical investigations of two prototypical heterostructures: a metallic exchange-spring system (NiFe/CoFeB/MgO) and a hybrid ferromagnetic semiconductor-topological insulator (MnxGe1-x/Bi2Se3). In the former, complete IHLs occur under out-of-plane fields, accompanied by unprecedented asymmetric angular dependence of remanence, a hallmark of noncollinear magnetic configurations. Our minimal bilayer model reveals that such anomalous hysteresis universally originates from the interfacial nonlinear spin configurations induced by the synergistic effect of inhomogeneous magnetic parameters and anti-ferromagnetic exchange coupling, where IHL becomes energetically stabilized only when the interlayer coupling strength exceeds a critical threshold. Guided by this principle, we engineered the latter system, where Bi2Se3's spin texture couples antiferromagnetically with MnxGe1-x's magnetization, observing temperature-robust IHLs from 10 K to 250 K. Crucially, energy analysis demonstrates that the apparent "negative coercivity" corresponds to a metastable minimum in the free-energy landscape, reconciling IHLs with fundamental thermodynamic laws. This work establishes interfacial coupling as a universal design rule for manipulating hysteresis topology, offering direct implications for spin-orbit torque devices and topological spintronic applications.

The development of van der Waals (vdW) ferromagnetic materials has triggered research toward low-power and highly integrated 2D spintronic devices. However, practical applications are hindered by limited Curie temperature (Tc), insufficient tunability of magnetic anisotropy, and scalability challenges. Here, wafer-scale vdW ferromagnetic Fe3GaTe2 was fabricated via molecular beam epitaxy. By precisely intralayer interstitial doping, the Tc of Fe3GaTe2 can be significantly enhanced from similar to 380 to similar to 590 K. 4D scanning transmission electron microscopy (4D-STEM) provides direct atomic-scale evidence for the formation of new intralayer Fe configurations. Meanwhile, this approach enables flexible manipulation of magnetic anisotropy, transitioning from perpendicular to in-plane magnetic anisotropy with the effective magnetic anisotropy constant (Keff) tuned from 0.57 to -2.099 J/cm3. This transition in magnetic anisotropy is attributed to the reduction of magnetocrystalline anisotropy, resulting from the weakened Fe 3d orbital moments, as confirmed by x-ray magnetic circular dichroism (XMCD). Theoretical analysis suggests that the extra intralayer Fe atoms contribute additional magnetic moments and enhanced exchange coupling, resulting in an increased Tc. Our findings pave a new pathway toward 2D magnetic materials with high Tc and tailored magnetic anisotropy, providing a scalable approach for room-temperature application of vdW spintronic devices.

Antiferromagnetic kagome metal FeGe has attracted tremendous attention in condensed matter physics due to the charge density wave (CDW) being well below its magnetic transition temperature. Up to now, numerous works on kagome FeGe have been based on single crystal bulk, but its thin film form has still not been reported. Here, we achieved epitaxial growth of FeGe thin films on Al2O3 substrates using molecular beam epitaxy. Structural characterization with x-ray diffraction, atomic force microscopy, and high-resolution scanning transmission electron microscopy reveals single phase with flat surface of kagome FeGe thin films. Moreover, a Néel temperature of 397 K and a rapid variation of Hall coefficient and magnetoresistance around 100 K, which might be related to the CDW, were revealed via transport measurements. The high quality kagome FeGe thin films are expected to provide a versatile platform to study the mechanism of CDW and explore the application of FeGe in antiferromagnetic spintronics.

Magnetic materials play a pivotal role in emerging fields such as new energy, information technology, and biomedicine, where accurate magnetic characterization is essential for material innovation and device engineering. Notably, with the burgeoning development of nanomaterials and spintronics, the importance of magnetic characterization has grown significantly, accompanied by increasingly higher requirements for precision and multi-dimensional analysis. This paper elaborates on the working principles and structural components of static magnetic measurement techniques—including Vibrating Sample Magnetometer (VSM), Alternating Gradient Magnetometer (AGM), Magneto-Optical Kerr Effect (MOKE) Microscope, Magnetic Force Microscope (MFM) and Superconducting Quantum Interference Device (SQUID) Magnetometer, as well as dynamic magnetic measurement techniques such as Alternating Current (AC) susceptometry and Ferromagnetic Resonance (FMR). In addition, this review also introduces emerging techniques relevant to spintronics, including Magnetometer based on negatively charged nitrogen-vacancy (NV−) centers in diamond, Spin-polarized Scanning Tunneling Microscope (SP-STM), Lorentz Transmission Electron Microscope (LTEM), and Soft X-ray-based techniques, highlighting their principles and applications in quantum sensing, magnetic imaging, and element-specific spin analysis. This overview emphasizes the unique capabilities and measurement principles of each magnetic characterization instrument, providing users with practical guidance to identify the most appropriate tool based on specific research objectives, material properties, and experimental requirements, thereby improving characterization efficiency and accuracy.

Multiferroic BiFeO3 (BFO) thin films have attracted significant attention for spintronic applications due to their strong magnetoelectric coupling at room temperature. However, the application of BFO remains at the laboratory stage, and low-temperature, large-scale preparation of BFO thin film still constitutes a challenge. In this study, the growth conditions of single-crystalline BFO, La-doped Bi1-xLaxFeO3 (BLFO), and ferromagnetic/BLFO heterostructures are optimized based on magnetron sputtering techniques. The following achievements are realized: 1) Epitaxial growth of BFO thin films at 440 degrees C, which is below the CMOS-compatible temperature; 2) Optimization of La doping at 550 degrees C to enhance the epitaxial quality (omega scan FWHM = 0.12), reduce leakage current (J(c) approximate to 10(-2) mA cm(-)(2)), and lower the ferroelectric switching voltage (1.83 V) of BLFO; 3) Achievement of a large exchange bias (Hex = 85.1 Oe) with Hex/coercive field(Hc)>1 in CoFeB/BLFO heterostructures. These achievements advance the broader application of BFO and lay the foundation for voltage-controlled field-free switching in ultra-low-power spintronic devices.

Magnetic anisotropy modulation is central to spintronics. 2D ferromagnetic materials (2D FMs), with their atomic‐level thickness, tunable electronic structures, and high sensitivity to external stimuli, provide unprecedented opportunities for precise magnetic control. Particularly, the van der Waals (vdW) gap holds promise for effective magnetic anisotropy modulation. However, the microscopic mechanisms remain elusive. Here, it is demonstrated that epitaxial growth of α‐Al 2 O 3 /Fe 4 GeTe 2 induces a pronounced expansion of the vdW gap (up to 0.51 Å) at the interface, leading to a robust enhancement of in‐plane magnetic anisotropy (IMA) and suppression of the spin reorientation temperature ( T SR ) from 288 K to undetectable levels. This counterintuitive behavior contrasts with conventional thickness‐dependent perpendicular magnetic anisotropy (PMA). Combined experimental and theoretical analyses reveal that vdW gap expansion reduces Te p x /p y orbital overlap, diminishing their contribution to magnetocrystalline anisotropy energy and suppressing PMA. These findings establish interface gap engineering as a novel route for tailoring magnetic anisotropy in 2D FMs, advancing the design of next‐generation spintronic devices.

Haptic technology has the potential to bring tactile richness to touchscreens on smartphones, tablets, and laptops, unlocking new dimensions for digital interaction and communication. Yet, despite notable advancements in visual resolution, the resolution of tactile pixels-referred to as "taxels"-lags significantly behind, limiting the immersive tactile feedback required for a truly enriched user experience. To bridge this gap, the study presents a transparent haptic interface with a 3D architecture that dynamically reconfigures high-resolution taxels through a densely integrated actuator array. Each actuator can be precisely inflated through fluid pressure to deliver tactile feedback with exceptional clarity and density, surpassing both the tactile perception and two-point discrimination thresholds of human fingertips. This haptic interface reveals transformative potential for enhancing touchscreen interactions in applications such as touch panel control, virtual exploration, and gaming, as it can be reversibly attached to various touchscreens and create nuanced topographical features that align with on-screen visuals.

Dzyaloshinskii-Moriya interaction (DMI) is a key driver of chiral magnetism and has garnered significant interest in applied magnetism and spintronics. Interface engineering has been demonstrated to effectively enhance the DMI in many traditional heterostructures. The regulation of DMI is highly dependent on interface properties, which vary significantly across different material systems. Therefore, determining the optimal interface structure to maximize the DMI value presents a complex challenge. In this work, Brillouin light-scattering (BLS) spectroscopy quantitatively reveals a strong interfacial DMI of 17 μJ/m2 in Py/Ti (tTi)/CoFeB/MgO heterostructures with robust perpendicular magnetic anisotropy when the thickness of the Ti layer is 2 nm. Furthermore, we employed a field-modulated magneto-optical Kerr-effect microscope (MOKE) to visualize the existence of stable labyrinth domains in real space in the Py/Ti (2 nm)/CoFeB/MgO systems, which might be able to induce further skyrmions. By optimizing the thickness of a specific membrane configuration, this paper offers a critical materials foundation for advancing spintronics applications.

In spintronics, characterizing the temperature dependence of spin Hall angle (SHA) has been a common method to explore the underlying mechanisms of spin Hall effect (SHE). However, the experimental reports of orbital Hall effect (OHE) under varying temperatures remain limited. Here, we systematically investigate the effective charge-to-spin conversion efficiencyθHin Ta/Ni and Ta/CoFeB bilayers across the temperature ranging from 10 K to 300 K, where theθHrepresents the combined contribution of the SHA and the orbital Hall angle (OHA). TheθHof Ta/Ni remains positive across the investigated temperature range, indicating that the OHE dominates over the SHE. The Ta/CoFeB sample serves as a reference with negligible OHE, exhibiting negative values ofθHthat are consistent with the SHA of Ta. As temperature decreases, theθHof both Ta/Ni and Ta/CoFeB increase with similar trends. Due to the significantly smaller difference of SHAs in Ta/Ni and Ta/CoFeB compared to those of OHAs, we suggest that the similar trends ofθHdemonstrate the weak temperature dependence of OHA in Ta/Ni. This finding advances the comprehensive understanding of OHE and may pave the way for the application of orbitronics.

We present a device integrated thermal and optical induced phase change materials vanadium dioxide and spin–orbit torque magnetic tunnel junction. This device showcases the ability to perform in-memory sensing and computing under thermal and optical stimulus, manifesting multiple logic functions in response to different input signals. Furthermore, a circuit simulation model based on the experimental results is built, which can implement 16 types of reconfigurable Boolean logic gates. On this basis, a 1 kb half-adder Magnetoresistive Random Access Memory (MRAM) array is constructed that significantly enhancing the computational throughput.

Multiferroic BiFeO 3 (BFO) thin films have attracted significant attention for spintronic applications due to their strong magnetoelectric coupling at room temperature. However, the application of BFO remains at the laboratory stage, and low‐temperature, large‐scale preparation of BFO thin film still constitutes a challenge. In this study, the growth conditions of single‐crystalline BFO, La‐doped Bi 1‐x La x FeO 3 (BLFO), and ferromagnetic/BLFO heterostructures are optimized based on magnetron sputtering techniques. The following achievements are realized: 1) Epitaxial growth of BFO thin films at 440 °C, which is below the CMOS‐compatible temperature; 2) Optimization of La doping at 550 °C to enhance the epitaxial quality (ω scan FWHM = 0.12), reduce leakage current (J c ≈ 10 −2 mA cm − 2 ), and lower the ferroelectric switching voltage (1.83 V) of BLFO; 3) Achievement of a large exchange bias ( H ex = 85.1 Oe) with H ex /coercive field( H c )>1 in CoFeB/BLFO heterostructures. These achievements advance the broader application of BFO and lay the foundation for voltage‐controlled field‐free switching in ultra‐low‐power spintronic devices.

In this study, fiber Bragg grating (FBG) magnetic field sensors with an improved sensitivity were achieved through magnetic field biasing and pre-stress regulation. Firstly, a multi-physics coupling model was developed by integrating magnetostrictive theory with FBG strain sensing principles. Three sensor structures were designed: a baseline without optimization, one optimized with a bias magnetic field, and one optimized with axial precompressive stress. Experimental results showed that the sensor's sensitivity under a bias magnetic field of 33.7 mT increased to 11.55 pm/mT, which was 68.18 % higher than that of the unoptimized case. When an axial pre-compressive stress of -10 MPa was applied, the sensitivity further increased to 14.17 pm/mT, which was total 106.26 % higher than that of the unoptimized case. This work offers a novel strategy for the sensitivity optimization in magnetic field sensors, suggesting its promising applications in miniaturized and highly integrated magnetic sensing systems.

Voltage-controlled magnetic anisotropy (VCMA) has emerged as a potential solution to significantly reduce the power consumption of next-generation magnetic random-access memory (MRAM). There are still great challenges in manipulating the VCMA effect and achieving a large VCMA value. In this work, we utilized Mg insertion to enhance VCMA and revealed the transient anisotropy variation characteristics during the voltage-controlled process in CoFeB/MgO based magnetic tunnel junction structures. The hysteresis loops extracted from the anomalous Hall effect show a split during multiple scans at different voltages, where the amplitude of the split changes regularly with the voltage and scanning times. There are more obvious splitting states in the cases of negative voltage compared to positive voltage, and no influence is shown in the situation with zero voltage. This transient state persists, and it is an intermediate state that gradually stabilizes and eventually reaches equilibrium after several scans; this behavior is related to the interfacial migration of oxygen ions due to the combined influence of the external voltage and high Mg–O binding energy. Our work provides insights into the underlying mechanisms of VCMA in CoFeB/MgO based structures, which provides a foundation for further study of the magnetic anisotropy manipulation in the practical application of MRAM.

Spintronic devices have become a crucial technology for overcoming the power consumption bottleneck in integrated circuits, due to their low power consumption, high-speed processing capability. Two-dimensional materials offer potential for performance enhancement and device miniaturization in spintronics because of their unique electronic and spin properties. Specifically, two-dimensional transition metal dichalcogenides (2D TMDs) are favored in the field of spintronics for their strong spin–orbit coupling effects, enabling effective control over the electron spin state. However, the preparation techniques for 2D TMDs are still in the exploratory stage. In this work, we explore novel preparation method combining magnetron sputtering and molecular beam epitaxy, leading to wafer-scale high-quality monocrystalline PtTe2 thin films. Further, Spin-Orbit Torque (SOT) efficiency is investigated in PtTe2-based heterostructures, which reveals a significant spin Hall angle of over 0.094. Our work provides a new way to fabricate the wafer-scale PtTe2 thin films and confirms a large SOT efficiency, which indicates the great promise for spintronic applications.

Schematics (a and b) and eigenstates (c and d) of 1H (a and c) and 3H (b and d) devices.

Objective: Respiratory regulation is critical for patients with respiratory dysfunction. Clinically used ventilators can lead to long-term dependence and injury. Extracorporeal assistance approaches such as iron-lung devices provide a noninvasive alternative, however, artificial actuator counterparts have not achieved marvelous biomimetic ventilation as human respiratory muscles. Here, we propose a bionic soft exoskeleton robot that can achieve extracorporeal closed-loop respiratory regulation by emulating natural human breath. Methods : For inspiration, a soft vacuum chamber is actuated to produce negative thoracic pressure and thus expand lung volume by pulling the rib cage up and outward through use of external negative pressure. For expiration, a soft origami array under positive pressure pushes the abdominal muscles inward and the diaphragm upward. To achieve in vitro measurement of respiratory profile, we describe a wireless respiratory monitoring device to measure respiratory profiles with high accuracy, validated by quantitative comparisons with spirometer as gold-standard reference. By constructing a human-robot coupled respiratory mechanical model, a model-based proportional controller is designed for continuous tracking of the target respiratory profile. Results: In experiments with ten healthy participants and ten patients with respiratory difficulty, the robot can adjust its assistive forces in real time and drive human-robot coupling respiratory system to track the target profile. Conclusion : The biomimetic robot can achieve extracorporeal closed-loop respiratory regulation for a diverse population. Significance : The soft robot has important potential to assist respiration for people with respiratory difficulty, whether in a hospital or a home setting.

Layered two-dimensional ferromagnetic materials have emerged as a promising platform for spintronic applications, owing to their extraordinary physical properties. Remarkably, the representative two-dimensional ferromagnet Fe3GeTe2 has been extensively investigated due to its high Curie temperature and strong perpendicular magnetic anisotropy, which are beneficial for high-density storage at room temperature. However, there are few reports on its stability in the air and the surface oxidation products, which may prohibit its future application. Here, we report the natural oxidation process of Fe3GeTe2 films grown by molecular beam epitaxy evolved in the atmosphere, which was studied by x-ray photoelectron spectroscopy measurements and transmission electron microscopy. Our research shows that the surface of the Fe3GeTe2 film is oxidized quickly when exposed to air and shows two obviously evolving stages in the whole oxidation process. In the first stage, metallic Ge atoms are almost completely oxidized to form Ge–O bonds in GeO2, while partial metallic Fe and Te atoms are oxidized into Fe2O3 and TeO2, respectively. The second stage of oxidation is dominated by changes in the valence state of the Fe element, where Fe2O3 is reduced to FeCO3 through the participation of carbon adsorbed on the surface with the final oxidation product of FeCO3 · GeO2 · TeO2. Our findings provide insight into the subsequent growth and protection of Fe3GeTe2 thin films, which is of great significance for in-depth study and further application of spintronic devices in two-dimensional limits.