Browse Articles

Enhancing the fatigue performance of laminated hafnium zirconium oxide ferroelectric thin films via reducing interfacial charge density

Laminated HfO2-based ferroelectric thin films show great promise for applications in high-density ferroelectric field-effect transistor memories, nanoelectromechanical system resonators, and energy storage devices. However, the polarization fatigue performance of widely investigated Hf0.5Zr0.5O2 (HZO)/Al2O3/HZO laminated films remains poor. In this work, we propose a novel laminated ferroelectric film, HZO/HfN/HZO, to enhance the fatigue performance. Compared with HZO/Al2O3/HZO thin films, the HZO/HfN/HZO films demonstrate significantly enhanced fatigue resistance, enduring up to 1 × 108 cycles at a measurement frequency of 100 kHz and exhibiting slower polarization degradation. This improvement is revealed to stem from a reduced interface trap charge density. Moreover, the lower trap density is attributed to the smaller electric field across the HfN layer that suppresses its degradation and a bandgap comparable to HZO that minimizes carrier energy release at the HfN/HZO interface. This work presents a key step for developing highly reliable laminated HfO2 ferroelectric films and devices.

Decoupled modulation of the degree of optical polarization and emission wavelength in far-UVC-LEDs: A staggered quantum wells strategy

The inherently poor light extraction efficiency severely limits the application of AlGaN-based far-ultraviolet-C (far-UVC) light emitting diodes (LEDs) (<240 nm). This originates from the ultra-high Al composition of quantum wells required for short-wavelength emission, which induces a transverse magnetic dominant optical polarization and inevitably causes serious total internal reflection. To reconcile the degree of optical polarization (DOP) and emission wavelength, a function divisional strategy utilizing staggered Al composition quantum wells is proposed in this architecture, where the low-Al and high-Al layers separately govern the DOP and wavelength through the modulation of valence and conduction band, respectively. Consequently, the DOP of quantum wells is reversed from −40% to ∼16% at an emission wavelength of 236 nm, enabling transverse electric-dominant vertical emission. Thanks to it, the far-UVC-LEDs exhibit a light output power of 3.13 mW at 400 mA and a peak wall plug efficiency of 0.13% at 100 mA, showing enhancements severally of 12.2% and 34.7% over the conventional structures. This strategy is highly compatible with commercial metal-organic chemical vapor deposition, offering a robust pathway for high-performance far-UVC-LEDs.

Role of spatiotemporal nonuniformities in laser-induced magnetization precession damping

Laser-induced magnetization precession measurements in ferromagnets often reveal an anomalous decrease in damping time near a field-induced second-order spin-orientation transition, a behavior that cannot be described by the linearized Landau–Lifshitz–Gilbert equation. Here, we demonstrate that this anomaly is not a material property but results from interference of precessing local magnetizations within the inhomogeneously excited region. By combining pump–probe experiments, analytical modeling that accounts for finite pump and probe spot sizes, and micromagnetic simulations, we show that the standard macrospin approach fails to capture the observed dynamics. The inhomogeneous relaxation of magnetic parameters within the excitation area distorts the measured precession envelope, while dipole fields give rise to a temporally non-monotonic term in its frequency. Our results highlight the critical role of excitation locality in the vicinity of critical fields.

Analysis of native oxides grown on single-crystal CdTe and MgCdTe

Over the course of CdTe photovoltaics development, many refinements to the device stack have been made. One area of current interest is the back contact interface, where surface passivation is critical to prevent recombination at the interface. One candidate material for achieving strong passivation is TeO2. Using scanning transmission electron microscopy, we investigate native oxide formations on CdTe and MgxCd1−xTe substrates to better understand the oxides' chemical composition and the interface they form with the material they are grown on. We find that substoichiometric TeOx forms as a native oxide on CdTe, and on MgxCd1−xTe, we found a MgO native oxide. Some TeOx appeared atop the MgO layer, though it was not consistently present. The native oxides had preferential interface terminations, with Cd terminations at the CdTe/TeOx interface and Te terminations at the MgxCd1−xTe/MgO interface.

An electrically isolated Josephson junction array as a tunable metamaterial

We report low-temperature microwave transmission measurements on a superconducting metamaterial composed of an electrically isolated two-dimensional Josephson junction (JJ) array. Each plaquette, which acts as a meta-atom, is a square loop with a single JJ centered on each side. The collective response of approximately 30 000 coupled meta-atoms produces a sharp, robust resonance in transmission. The resonance can be switched on and off, and its frequency and amplitude tuned, by varying temperature or incident microwave power. Above a threshold rf power of approximately −49 dBm the resonance evolves into multiple discrete transmission features with uniform frequency spacing. These observations indicate a power-dependent nonlinear response, consistent with frequency-locking phenomena in Josephson systems. Moreover, our results demonstrate how an unbiased JJ array can function as a nonlinear, tunable electromagnetic metamaterial in the microwave regime.

Ultrafast vibrational dynamics: An impulsively stimulated resonance Raman perspective

Accessing excited-state vibrations is crucial to elucidate physical and chemical properties of photoreactive molecules and solids. Time-resolved resonance Raman spectroscopy provides unique vibrational fingerprints of different electronic levels, but its spontaneous version often suffers from strong fluorescence backgrounds and has its spectral/temporal resolutions fundamentally limited by the Fourier principle, hindering spectral assignments and the investigation of ultrafast dynamics. Here, we discuss how these issues can be overcome using Impulsive Stimulated Raman spectroscopy, a pump-probe technique that tracks coherent vibrational motion on different electronic states in real time. Using the highly fluorescent cyanine dye IR-775 as an experimental benchmark, we show that broadband probe detection isolates Raman spectra across different resonances, enabling unambiguous excited-state assignment. The time-domain scheme effectively measures fluorescence-free spectra, revealing a low-frequency Raman mode at 130 cm−1 in the electronic ground and first excited states, which plays a critical role in vibronic coupling with higher-lying electronic levels. Finally, we highlight the technique's versatility in light of recent experiments and related perspectives. These include two-color schemes with pulses spanning from X-rays to the infrared, the use of pulse chirp as a powerful control knob to unveil specific spectroscopic signatures, and strategies to amplify the scattering cross section.

Artificial Gap Junctional Channel Inhibiting the Proliferation of Hepatocellular Carcinoma Cells

ABSTRACT Gap junctions play a crucial role in intercellular communication, participating in both physiological and pathological processes. Although artificial gap junctions have been developed, their physiological functions beyond basic intercellular communication remain largely unexplored. Herein, we report a functional artificial gap junctional channel system constructed via electrostatic co‐assembly of an amphiphilic transmembrane channel and a hydrophilic extracellular channel. The efficient ion transport capability of the amphiphilic channel, coupled with the extensive aggregation of the hydrophilic module within the intercellular gap, enables the formation of stable intercellular junctions. Similar to natural gap junctions, these artificial channels not only mediate intercellular ion transport but also induce G1 phase cell cycle arrest and inhibit the proliferation of hepatocellular carcinoma cells. This work provides a new strategy for intervening in cell–cell communication and offers a potential therapeutic avenue for cancer and gap junction‐related diseases.

Subregional and laminar specializations of pyramidal neurons in the macaque anterior cingulate cortex

The anterior cingulate cortex (ACC)—a component of both the limbic system and the frontal-executive network—is composed of three anatomically distinct subregions with diverse roles in processing cognitive and emotional information: rostral area 32 (A32), dorsal area 24 (A24), and ventral area 25 (A25). Pyramidal neurons (PYRs) as the neural substrates of cortical communication govern signal processing and integration differently across brain regions, layers and pathways. Their properties and diversity across the heterogenous ACC subregions have yet to be comprehensively characterized in primates. Here, we compared the biophysical and morphological properties of PYRs in layers 2-3 (L2-3) and 5-6 (L5-6) across ACC subregions of young adult rhesus monkeys (8 females, 11 males) using in-vitro whole-cell patch clamp recording with intracellular filling. Results showed the more pronounced laminar differences in biophysical properties of PYRs in A24 and 32 than in A25, that L2-3 PYRs exhibited lower excitability than L5-6 PYRs. Further, A32 contained a higher proportion of cells receiving high-frequency-sEPSC, with L2-3’s enrichment of mushroom spines compared to L5-6. This heterogeneity in laminar differentiation aligns with cytoarchitectural differences across ACC subregions and suggests layer-specific signaling and excitatory drive in A24 and A32. In contrast, A25 showed cellular heterogeneity in firing patterns as well as different inhibitory signaling dynamics from other ACC subregions. Together, these results highlight the heterogeneity in laminar differentiation of PYR properties across ACC subregions, contributing to their diverse circuits and roles in cognitive-emotional integration and disruption in disease. Significance Statement ACC is a heterogeneous region comprising functionally distinct cytoarchitectonic subregions. Our understanding of the heterogeneity of primate ACC has been derived mainly from anatomical data or limited in-vivo electrophysiological studies. This study assessed the properties of pyramidal neurons (PYRs), the fundamental unit of cortical communication, across primates ACC subregions and layers. Our results demonstrate that, although laminar position is a strong determinant of PYR properties across ACC, the magnitude of these laminar differences varies by subregion—from A24 to A25 exhibiting the most to least-pronounced laminar distinctions. These specializations across ACC subregions mirror the gradients in cytoarchitectural, developmental and connectional patterns, and likely support distinct signal processing and network integration underlying cognitive-emotional control through specialized local and long-range circuits.

Genetic Targeting and Conductance-Based Modeling Reveal Novel Diversity Within Mouse Type II Spiral Ganglion Neurons

Spiral ganglion neurons (SGNs) transmit auditory signals from the cochlea to the brain and are divided into two main types: type I and type II, distinguished by their anatomy and connectivity. However, the function of type II SGNs remains poorly understood due to their scarcity and lack of clear physiological markers. In this study, we use two Cre-dependent fluorescent reporter mouse lines of both sexes to enhance the identification and targeting of type II SGNs for whole-cell patch-clamp recordings. We reveal a set of distinguishing biophysical features, most notably, the presence of an inactivating potassium current and weaker voltage-gated sodium currents, that clearly separate type II SGNs from their type I counterparts. Additionally, we uncover greater-than-expected heterogeneity among type II SGNs, including variation in size, excitability, and ion channel expression. These features suggest the existence of distinct subtypes of type II SGNs, with potential differences in function. We find that most type II SGNs are relatively unexcitable and incapable of repetitive firing. Instead, they appear to be better suited to integrating sustained signals, potentially supporting roles in detecting cochlear damage or modulating efferent feedback. Additionally, through computational modeling, we demonstrate that removing the inactivation component of the inactivating potassium current specific to type II SGNs allowed repetitive spiking to similar levels seen in type I SGNs, suggesting a crucial role for the current in stifling type II SGN activity. Together, our findings define biophysical signatures that distinguish SGN types and subtypes, offering new insight into their contributions to normal hearing and cochlear pathology. Significance Statement The sensory neurons of the cochlea are divided into type I and type II spiral ganglion neurons. Type I spiral ganglion neurons convey the main features of sound information. The rarer type II spiral ganglion neurons appear to be putative auditory nociceptors, responding to cochlear damage. By combining genetic tools, electrical activity recordings, and computational models, we demonstrate that type I and type II spiral ganglion neurons have distinctive ion channel profiles and firing properties. Furthermore, we report previously undescribed ion channel diversity within the type II spiral ganglion neuron population, suggesting varied functions. Our results highlight the parallels between type II spiral ganglion neurons and somatosensory nociceptors and provide a framework for selectively targeting distinct auditory neuron populations.

Surface Terminations of LaAlO ₃ Perovskite Nanoparticles as Viewed by Solid-State Nuclear Magnetic Resonance

Decoupled Molecular Motifs and Supramolecular Dimers for Highly Efficient FDCA Synthesis from Neutral Biomass

Platinum Ensemble Heterogeneity Enables Efficient Solvent-Free Hydrogen Production

Diameter-Controlled Synthesis of Horizontally Aligned Carbon Nanotube Arrays via S-Apphire Interface Engineering

Precision Synthesis of I–III–VI Ternary Semiconductor Nanoclusters via Self-Limiting Cation Exchange

Supramolecular Modulation of Controlled Radical Polymerization

Actively Programming Battery Chemistry via Pulse Modulation

Frozen-State Electrochemistry Enables Proton-Selective Reaction Environments for Deterministic Atomic Construction

Programmable DNA-Based Dimerization Networks for Dynamic and Competitive Control of Transcription

A Nonbenzenoid Nanographene Horse Saddle With Four Pentagon–Octagon Pairs

ABSTRACT The incorporation of non‐hexagonal rings into nanographenes (NGs) would significantly alter their geometry and electronic structures, unlocking new application potential. However, the precise integration of consecutive pentagon–octagon into NGs remains synthetically challenging due to the associated high strain and the limitation in design strategy. Herein, we report an unprecedented horse‐saddle non‐benzenoid NG ( HN1 ) embedding four pairs of pentagon–octagon units. The synthesis proceeds through two key steps: a tetramerization of 3‐bromoacenaphthylen‐1(2 H )‐one, followed by a three‐fold Pd‐catalyzed annulation with a diacetylene derivative. Single‐crystal X‐ray diffraction confirms that HN1 adopts a unique horse‐saddle geometry induced by the four adjacent octagons. The fused pentagon–octagon pairs of NG impart configurational stability, high solubility, multiple reversible redox behavior, and a distinct antiaromatic character arising from the core structure. Notably, the incorporation of HN1 as an additive in the perovskite active layer significantly enhanced the power conversion efficiency (PCE) of perovskite solar cells from 20.60% to 22.61%. This work not only provides a synthetic approach to negatively curved NGs with contiguous nonhexagonal motifs but also explores their promising application in emerging optoelectronic devices.

Catalytic Asymmetric Cationic Geranyl Cyclizations