Brain-inspired neuromorphic computing has shown great promise beyond the conventional Boolean logic. Nanoscale electronic synapses, which have stringent demands for integration density, dynamic range, energy consumption, etc., are key computational elements of the brain-inspired neuromorphic system. Ferroelectric tunneling junctions have been shown to be ideal candidates to realize the functions of electronic synapses due to their ultra-low energy consumption and the nature of ferroelectric tunneling. Here, we report a new electronic synapse based on a three-dimensional vertical Hf0.5Zr0.5O2-based ferroelectric tunneling junction that meets the full functions of biological synapses. The fabricated three-dimensional vertical ferroelectric tunneling junction synapse (FTJS) exhibits high integration density and excellent performances, such as analog-like conductance transition under a training scheme, low energy consumption of synaptic weight update (1.8 pJ per spike) and good repeatability (>103 cycles). In addition, the implementation of pattern training in hardware with strong tolerance to input faults and variations is also illustrated in the 3D vertical FTJS array. Furthermore, pattern classification and recognition are achieved, and these results demonstrate that the Hf0.5Zr0.5O2-based FTJS has high potential to be an ideal electronic component for neuromorphic system applications.

The addition of numerous main metal elements into highentropy alloys (HEAs) have been popular since their discovery in 2004. [2] This has provided a vast combinatorial space for the exploration of new materials with unexplored abnormal functionalities. In general, four core factors, namely, sluggish diffusion, configurational entropy, lattice distortion, and cocktail effects, affect the crystal structure and properties of HEAs. [3] Since 2015, the concept of high entropy has been successfully expanded to include oxides. [4] Similar to HEAs, high-entropy oxides (HEOs) are defined as compositions consisting of oxygen and more than five metal cations in equimolar or near equimolar ratios in the range of 5-35% atomic concentration. [5] HEOs are rapidly emerging as delicate functional constituents that offer excellent compositional flexibility that permits the stabilization of numerous compositions with various crystal structures (e.g., rock-salt, spinel, fluorite, perovskite, and pyrochlore phases). [6] Consequently, HEOs present numerous attractive functional properties, such as high ionic conductivity; [7] superior storage capacity retention and good stable cycles of Li battery; [8] low thermal conductivity and good thermal stability; colossal dielectric constant; [9] and novel magnetic phenomena. [10] However, a deep understanding of their microstructures has yet to emerge. Thus, it is extremely urgent to learn more about the microstructure of HEOs to further understand their anomalous High-entropy oxides (HEOs), which incorporate multiple-principal cations into single-phase crystals and interact with diverse metal ions, extend the border for available compositions and unprecedented properties. Herein, a high-entropy-stabilized (Ca 0.2 Sr 0.2 Ba 0.2 La 0.2 Pb 0.2 )TiO 3 perovskite is reported, and the effective absorption bandwidth (90% absorption) improves almost two times than that of BaTiO 3 . The results demonstrate that the regulation of entropy configuration can yield significant grain boundaries, oxygen defects, and an ultradense distorted lattice. These characteristics give rise to strong interfacial and defect-induced polarizations, thus synergistically contributing to the dielectric attenuation performance. Moreover, the large strains derived from the strong lattice distortions in the high-entropy perovskite offer varied transport for electron carriers. The high-entropy-enhanced positive/negative charges accumulation around grain boundaries and strain-concentrated location, quantitatively validated by electron holography, results in unusual dielectric polarization loss. This study opens up an effective avenue for designing strong microwave absorption materials to satisfy the increasingly demanding requirements of advanced and integrated electronics. This work also offers a paradigm for improving other interesting properties for HEOs through entropy engineering.

An artificial synaptic device with a continuous weight modulation behavior is fundamental to the hardware implementation of the bioinspired neuromorphic systems. Recent reported synaptic devices have a less number of conductance states, which is not beneficial for the continuous modulation of weights in neuromorphic computing. Preparing a device with as many conductance states as possible is of great significance to the development of brain-inspired neuromorphic computing. Here, we present a two-terminal flexible organic synaptic device with ultra-multimodulated conductance states, realizing a face recognition functionality with a strong error-tolerant nature for the first time. The device shows an excellent long-term potentiation or long-term depression behavior and reliability after 1000 folded destructive tests. There are 600 continuous ultra-multimodulated conductance states, which can be used to realize the great face recognition capability. The recognition rates were 95.2% and above 90% for the initial and 15% noise pixel images, respectively. The strong error-tolerant nature indicates a potential application of a flexible organic artificial synaptic device with ultra-multimodulated conductance states in the large-scale neuromorphic systems.

Hydrogels exhibit potential applications in smart wearable devices because of their exceptional sensitivity to various external stimuli. However, their applications are limited by challenges in terms of issues in biocompatibility, custom shape, and self-healing. Herein, a conductive, stretchable, adaptable, self-healing, and biocompatible liquid metal GaInSn/Ni-based composite hydrogel is developed by incorporating a magnetic liquid metal into the hydrogel framework through crosslinking polyvinyl alcohol (PVA) with sodium tetraborate. The excellent stretchability and fast self-healing capability of the PVA/liquid metal hydrogel are derived from its abundant hydrogen binding sites and liquid metal fusion. Significantly, owing to the magnetic constituent, the PVA/liquid metal hydrogel can be guided remotely using an external magnetic field to a specific position to repair the broken wires with no need for manual operation. The composite hydrogel also exhibits sensitive deformation responses and can be used as a strain sensor to monitor various body motions. Additionally, the multifunctional hydrogel displays absorption-dominated electromagnetic interference (EMI) shielding properties. The total shielding performance of the composite hydrogel increases to ~ 62.5 dB from ~ 31.8 dB of the pure PVA hydrogel at the thickness of 3.0 mm. The proposed bioinspired multifunctional magnetic hydrogel demonstrates substantial application potential in the field of intelligent wearable devices.