Coulomb-induced emission time shifts in high-order harmonic generation from H2.

Accurate emission times of high-order harmonic generation (HHG) are vital for high-precision ultrafast detection in attosecond science, but a quantitative analysis of Coulomb effects on this time is absent in the molecular HHG. Here, we investigate the Coulomb-induced emission-time shift in HHG of H2+ with two different internuclear distances R, where the times obtained via the Gabor transform of numerical data from solving the time-dependent Schrödinger equation are used as simulation experiment results. Based on the molecular strong-field approximation, we develop a trajectory-resolved classical model that takes into account the molecular two-center structure. By selecting appropriate electron trajectories and including Coulomb interactions, the classical trajectory method can reproduce Gabor emission times well. This consistence reveals that Coulomb tails cause an emission-time shift of ∼35 as at the R = 2.0 a.u. case and of ∼40-60 as at the R = 2.6 a.u. case under the present laser parameters when compared to the Coulomb-free quantum-orbit model. Our results are of significance to probe the attosecond dynamics via two-center interference.

Methodology for Testing Key Parameters of Array-Level Small-Area Hafnium-Based Ferroelectric Capacitors Using Time-to-Digital Converter and Capacitance Calibration Circuits.

Hafnium-based ferroelectric memories are a promising approach to enhancing integrated circuit performance, offering advantages such as miniaturization, compatibility with CMOS technology, fast read and write speeds, non-volatility, and low power consumption. However, FeRAM (Ferroelectric Random Access Memory) still faces challenges related to endurance and retention susceptibility to process variations. Hence, testing and obtaining the core parameters of ferroelectric capacitors continuously is essential to investigate these phenomena and explore the potential solution. The traditional method for measuring ferroelectric capacitors has limitations in timing generation capability, introduces parasitic capacitance, and lacks accuracy for small-area capacitors. In this study, we analyzed the working principle of ferroelectric capacitors and designed a method to detect the remnant polarization, saturation polarization, and imprint offset of ferroelectric capacitors. Further, we further proposed a circuit implementation method. The proposed test circuit conquers these limitations and enables high-precision testing of ferroelectric capacitors, contributing to developing hafnium-based ferroelectric memories. The circuit includes a flip-readout circuit, a capacitance calibration circuit, and a voltage-to-time converter and time-to-digital converter (VTC&TDC) readout circuit. According to simulation results, the capacitance calibration circuit reduces the deviation of the capacitance by 84%, and the accuracy of the readout circuit is 5.91 bits, with a readout time of 150 ns and a power consumption of 1 mW. This circuit enables low-cost acquisition of array-level small-area ferroelectric capacitance data, which can guide subsequent device optimization and circuit design.

Oxygen-deficient TiO2-x interlayer enabling Li-rich Mn-based layered oxide cathodes with enhanced reversible capacity and cyclability.

The unique anion redox mechanism of Li-rich Mn-based layered oxide (LMLO) cathodes endows them with a higher specific capacity compared with conventional cathodes. However, the irreversible anion redox reactions can cause structural degradation and sluggish electrochemical kinetics in the cathode, resulting in a poor electrochemical performance in the batteries. Thus, to address these issues, a single-sided conductive oxygen-deficient TiO2-x interlayer was applied on a commercial Celgard separator as a coating layer towards the LMLO cathode. After coating TiO2-x, the initial coulombic efficiency (ICE) of the cathode increased from 92.1% to 95.8%, the capacity retention improved from 84.2% to 91.7% after 100 cycles, and the rate performance of the cathode was significantly enhanced from 91.3 mA h g-1 to 203.9 mA h g-1 at 5C. Operando differential electrochemical mass spectroscopy (DEMS) showed that the coating layer could restrain the release of oxygen in the battery, especially from the initial formation process. The X-ray photoelectron spectroscopy (XPS) results demonstrated that the favorable oxygen absorption by the TiO2-x interlayer benefitted the suppression of side reactions and cathode structural evolution and favored the formation of a uniform cathode-electrolyte interphase on the LMLO cathode. This work provides an alternative path to address the issue of oxygen release in LMLO cathodes.

Mitigation of Oxygen Evolution and Phase Transition of Li-Rich Mn-Based Layered Oxide Cathodes by Coating with Oxygen-Deficient Perovskite Compounds.

Li-rich Mn-based layered oxide cathodes with a high discharge capacity hold great promise for high energy density lithium-ion batteries. However, application is hampered by voltage and capacity decay and gas evolution during cycling due to interfacial side reactions. Here, we report coating by oxygen-deficient perovskite La0.9Sr0.1CoO3 using the Pechini process. X-ray photoelectron spectroscopy and scanning transmission electron microscopy both exhibit a uniform coating layer with a high oxygen vacancy concentration. The coating effectively mitigates the first cycle irreversible capacity loss and voltage decay while increasing cyclability. Optimized coating improves capacity retention from 55.6% to 84.8% after 400 cycles at 2 C. Operando differential electrochemical mass spectroscopy shows that such a coating can significantly mitigate the release of oxygen and carbon dioxide. Electrochemical impedance spectroscopy and post-mortem analysis indicate that the coating layer forms a stable interface and restricts structure evolution and cation mixing during cycling, conferring these cathode materials with better cycling and voltage stability. The perovskite can be applied to other cathodes with high voltage and capacity to suppress interfacial side reactions toward developing stable high energy density batteries.

Probabilistic Circuit Implementation Based on P-Bits Using the Intrinsic Random Property of RRAM and P-Bit Multiplexing Strategy.

Probabilistic computing is an emerging computational paradigm that uses probabilistic circuits to efficiently solve optimization problems such as invertible logic, where traditional digital computations are difficult to solve. This paper proposes a true random number generator (TRNG) based on resistive random-access memory (RRAM), which is combined with an activation function implemented by a piecewise linear function to form a standard p-bit cell, one of the most important parts of a p-circuit. A p-bit multiplexing strategy is also applied to reduce the number of p-bits and improve resource utilization. To verify the superiority of the proposed probabilistic circuit, we implement the invertible p-circuit on a field-programmable gate array (FPGA), including AND gates, full adders, multi-bit adders, and multipliers. The results of the FPGA implementation show that our approach can significantly save the consumption of hardware resources.

Single-Crystalline Cathodes for Advanced Li-Ion Batteries: Progress and Challenges.

Single-crystalline cathodes are the most promising candidates for high-energy-density lithium-ion batteries (LIBs). Compared to their polycrystalline counterparts, single-crystalline cathodes have advantages over liquid-electrolyte-based LIBs in terms of cycle life, structural stability, thermal stability, safety, and storage but also have a potential application in solid-state LIBs. In this review, the development history and recent progress of single-crystalline cathodes are reviewed, focusing on properties, synthesis, challenges, solutions, and characterization. Synthesis of single-crystalline cathodes usually involves preparing precursors and subsequent calcination, which are summarized in the details. In the following sections, the development issues of single-crystalline cathodes, including kinetic limitations, interfacial side reactions, safety issues, reversible planar gliding and micro-cracking, and particle size distribution and agglomeration, are systematically analyzed, followed by current solutions and characterization techniques. Finally, this review is concluded with proposed research thrusts for the future development of single-crystalline cathodes.

Sensing Circuit Design Techniques for RRAM in Advanced CMOS Technology Nodes.

Resistive random access memory (RRAM) is one of the most promising new nonvolatile memories because of its excellent properties. Moreover, due to fast read speed and low work voltage, it is suitable for seldom-write frequent-read applications. However, as technology nodes shrink, RRAM faces many issues, which can significantly degrade RRAM performance. Therefore, it is necessary to optimize the sensing schemes to improve the application range of RRAM. In this paper, the issues faced by RRAM in advanced technology nodes are summarized. Then, the advantages and weaknesses in the novel design and optimization methodologies of sensing schemes are introduced in detail from three aspects, the reference schemes, sensing amplifier schemes, and bit line (BL)-enhancing schemes, according to the development of technology in especially recent years, which can be the reference for designing the sensing schemes. Moreover, the waveforms and results of each method are illustrated to make the design easy to understand. With the development of technology, the sensing schemes of RRAM become higher speed and resolution, low power consumption, and are applied at advanced technology nodes and low working voltage. Now, the most advanced nodes the RRAM applied is 14 nm node, the lowest working voltage can reach 0.32 V, and the shortest access time can be only a few nanoseconds.