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Antivortices have potential applications in future nano-functional devices, yet the formation of isolated antivortices traditionally requires nanoscale dimensions and near-zero magnetocrystalline anisotropy, limiting their broader application. Here, we propose an approach to forming antivortices in multiferroic ε-Fe2O3 with the coalescence of misaligned grains. By leveraging misaligned crystal domains, the large magnetocrystalline anisotropy energy is counterbalanced, thereby stabilizing the ground state of the antivortex. This method overcomes the traditional difficulty of observing isolated antivortices in micron-sized samples. Stable isolated antivortices were observed in truncated triangular multiferroic ε-Fe2O3 polycrystals ranging from 2.9 to 16.7 µm. Furthermore, the unpredictability of the polarity of the core was utilized as a source of entropy for designing physically unclonable functions. Our findings expand the range of antivortex materials into the multiferroic perovskite oxides and provide a potential opportunity for ferroelectric polarization control of antivortices. The creation of magnetic antivortices in two-dimensional magnets holds significant importance in spintronics. Here, the authors demonstrate the creation of stable antivortices in ε-Fe2O3 polycrystals by coalescing misaligned grains controllably. [ABSTRACT FROM AUTHOR]

The electrocatalytic nitrate reduction reaction (NO3−RR) presents a promising pathway for achieving both ammonia (NH3) electrosynthesis and water pollutant removal simultaneously. Among various electrocatalysts explored, 2D materials have emerged as promising candidates due to their ability to regulate electronic states and active sites through doping. However, the impact of doping effects in 2D materials on the mechanism of NO3−RR remains relatively unexplored. Here, Ni‐doped MoS2 (Ni‐MoS2) nanosheets are investigated as a model system, demonstrating enhanced NO3−RR performance compared to undoped counterparts. By controlling the doping concentration, the Ni‐MoS2 nanosheets achieve a remarkable faradic efficiency (FE) of 92.3% for NH3 at −0.3 VRHE with excellent stability. The mechanistic studies reveal that the elevation of the NO3−RR performances originates from the generation of more active hydrogen and the acceleration of the reaction from nitrite (NO2−) to NH3 facilitated by Ni doping. Combining the experimental observations and theoretical calculations it is revealed that the appropriate Ni doping level in MoS2 can enhance *NO3 adsorption strength, thereby facilitating subsequent electrocatalytic steps. Together with the demonstration of Zn−NO3− and Zn−NO2− battery devices, the work provides new insights into the design and regulation of the active sites in 2D material catalysts for efficient NO3−RR. [ABSTRACT FROM AUTHOR]

With the rapid developments of Artificial Intelligence (AI) and the Internet of Things (IoT), increasingly intricate and expanding application scenarios are placing higher demands on current machine vision capabilities. Therefore, there is a pressing need to simultaneously achieve diverse functionalities, simple designs, and efficient computing in vision devices. Here, the study develops a two‐terminal optoelectronic device utilizing a single 2D intrinsic defect semiconductor In2S3. The device demonstrates wavelength‐selective photodetection and neuromorphic visual capabilities, attributed to defect‐related charge‐trapping/de‐trapping processes. As a photodetector, the device exhibits a high photoresponsivity of 473.6 A W−1, a high external quantum efficiency of 1.6 × 105%, and a fast rise/fall time of 0.3/1.4 ms at the wavelength of 359 nm. As an all‐in‐one neuromorphic visual device, optoelectronic‐driven fundamental synaptic functions, including paired‐pulse facilitation (PPF), short‐term plasticity (STP), long‐term plasticity (LTP), and "learning‐experience", are successfully mimicked at the wavelength of 671 nm. Moreover, one‐shot recognition of the 12‐letter image "SHAN XI NORMAL" is achieved through an artificial convolutional neural network. This study provides a new strategy for developing compact high‐level intelligence systems for complex application scenarios. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) ferroionics is appealing in performing complex artificial intelligence tasks due to the interesting property of coexistence of ferroelectricity and ionic activities. CuInP2S6 (CIPS), as a typical 2D ferroionic material, is highly conducive to rich functions of information devices due to the displacement of Cu+ inducing both ferroelectricity and ionic conductivity. However, the coupling and modulation of polarization and ion migration in CIPS for multifunctional information devices has not been fully explored. Here, this study demonstrates that digital memory and synaptic simulations are realized in Au/CIPS/Au device via engineering ferroelectric polarization reversal and the long‐distance migration of the Cu+ to change conductive modes. Steep resistive switching behavior based on ion‐migration is observed with a high on/off ratio of over 108, long retention time (>2 × 104 s), and current compliance engineered multilevel resistance states, demonstrating reliable nonvolatile high‐density memory characteristics. Based on the continuous modulation of polar order, the key synaptic behaviors are successfully simulated. Moreover, by the co‐modulation of polarization state and ions migration, the paired‐pulse facilitation, paired‐pulse depression, and potentiation following depression are achieved. These results suggest that CIPS is a promising candidate for constructing high‐performance, function‐enriched devices for data storage, information processing, and neuromorphic computing. [ABSTRACT FROM AUTHOR]

Photoelectric synaptic devices with optical sensing capability are of great importance in simulating human vision systems. Especially realizing all‐in‐one vision neuristor on silicon based new materials and principles is being pursued. 2D van der Waals (vdW) materials have the unique advantage of arbitrary stacking on demand. Herein, a full‐vdW two‐terminal 2D ferroelectric α‐In2Se3/SnSe p–n heterojunction is proposed to construct an optoelectronic neuristor to simulate visual synaptic functions. Implementation of these simulations is attributed to the co‐modulation of the electrical polarization reconfigurable built‐in electric field caused by p–n junction and photo‐inducing ferroelectric polarization switching. These functions include ultra‐high paired‐pulse facilitation index (457%), short synaptic plasticity, long synaptic plasticity, and retina‐like optical adaptations. The high PPF is crucial for high‐precision decoding and processing of visual information. Meanwhile, the classical Pavlovian conditioned reflexes associated with associative learning are also emulated showing the ability of the device to handle complex electrical and optical inputs. This study demonstrates that two‐terminal ferroelectric p–n heterojunctions have great potential in high‐precision multifunctional optoelectronic visual synaptic devices. [ABSTRACT FROM AUTHOR]

The development and application of artificial intelligence have led to the exploitation of low‐power and compact intelligent information‐processing systems integrated with sensing, memory, and neuromorphic computing functions. The 2D van der Waals (vdW) materials with abundant reservoirs for arbitrary stacking based on functions and enabling continued device downscaling offer an attractive alternative for continuously promoting artificial intelligence. In this study, full 2D SnS2/h‐BN/CuInP2S6 (CIPS)‐based ferroelectric field‐effect transistors (Fe‐FETs) and utilized light‐induced ferroelectric polarization reversal to achieve excellent memory properties and multi‐functional sensing‐memory‐computing vision simulations are designed. The device exhibits a high on/off current ratio of over 105, long retention time (>104 s), stable cyclic endurance (>350 cycles), and 128 multilevel current states (7‐bit). In addition, fundamental synaptic plasticity characteristics are emulated including paired‐pulse facilitation (PPF), short‐term plasticity (STP), long‐term plasticity (LTP), long‐term potentiation, and long‐term depression. A ferroelectric optoelectronic reservoir computing system for the Modified National Institute of Standards and Technology (MNIST) handwritten digital recognition achieved a high accuracy of 93.62%. Furthermore, retina‐like light adaptation and Pavlovian conditioning are successfully mimicked. These results provide a strategy for developing a multilevel memory and novel neuromorphic vision systems with integrated sensing‐memory‐processing. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) van der Waals (vdW) magnetic materials with reduced dimensionality often exhibit unexpected properties compared to their bulk counterparts. In particular, the mechanical flexibility of 2D structure, enhanced ferromagnetism at reduced layer thickness, as well as robust perpendicular magnetic anisotropy are quite appealing for constructing novel spintronic devices. The vdW vanadium diselenide (VSe2) is an attractive material whose bulk is paramagnetic while monolayer is ferromagnetic with a Curie temperature (Tc) above room temperature. To explore its possible device applications, a detailed investigation on the thickness-dependent magnetism and strain modulation behavior of VSe2 is highly demanded. In this article, the VSe2 nanoflakes were controllably prepared via chemical vapor deposition (CVD) method. The few-layer single VSe2 nanoflakes were found to exhibit magnetic domain structures at room temperature. Ambient magnetic force microscopy (MFM) phase images reveal a clear thickness-dependent magnetism and the MFM phase contrast is traceable for the nanoflakes of layer thickness below ∼ 6 nm. Moreover, applying strain is found efficient in modulating the magnetic moment and coercive field of 2D VSe2 at room temperature. These results are helpful for understanding the ferromagnetism of high temperature 2D magnets and for constructing novel straintronic devices or flexible spintronic devices. [ABSTRACT FROM AUTHOR]

High‐performance stretchable and twistable nonvolatile memory devices with logic‐in‐memory functionality are highly desired for the development of future wearable electronics such as smart clothing. However, it is challenging to fabricate these memory devices using rigid functional materials based on conventional film deposition and patterning techniques. Herein, the first intrinsically stretchable and twistable resistive switching memory is reported using spin‐coated poly(dimethyl siloxane) elastomer as the storage medium and printed liquid metal as the electrodes. The memory device is found to exhibit a reliable resistive switching behavior under up to 30% stretching strain and 90° torsional deformation, possessing a large memory window (≈102) and an excellent retention (>104 s). Under 30% strain, stretching–release endurance of >500 cycles as well as excellent data integrity during the dynamic stretching–release process is demonstrated. Beyond data storage, logic‐in‐memory computation prototype represented by a one‐bit full adder is successfully implemented within four operation steps based on three stretched memory cells. This work will be highly valuable in materials and structure design towards the development of high‐performance and multifunctional wearable electronic modules and systems. [ABSTRACT FROM AUTHOR]