Nonlinear Hall effect in bilayer WTe2 induced by strong laser field

The geometric nature of Bloch electrons has recently come into focus of studies in nonlinear optics. In this regard, the Weyl semimetals, with their significant Berry curvature at Weyl nodes, are of particular interest. The recently discovered nonlinear Hall phenomena in Weyl semimetals (mainly 2nd order responses), provide a unique avenue to explore the topological properties of emergent quantum materials [1]. While previous studies in nonlinear optics have explored various mechanisms in Weyl semimetals, such as Bloch oscillations, intraband motions, and high harmonic generation, the relationship between nonlinear Hall phenomena and nonlinear optics remains unexamined. Our study presents the first investigation of the relationship between nonlinear Hall effects and nonlinear optical responses in Weyl Dirac nodes, ranging from perturbative to nonperturbative regimes. Focusing on the mid-infrared frequency range, we probe the effects of intensity and frequency dependence, including energy cutoffs and the interplay between interband and intraband processes, using time-dependent first-principles formalismjournal articl

Robust quantum spin liquid state in the presence of giant magnetic isotope effect in D3LiIr2O6

The deuterium isotope effect on the honeycomb iridate H3LiIr2O6, a quantum spin-orbit-entangled liquid, was examined by synthesizing D3LiIr2O6. The structural refinements indicate the different character of the interlayer OH and OD bonds, which results in a giant isotope effect on the magnetic interactions; the antiferromagnetic Curie-Weiss temperature |θCW| of D3LiIr2O6 increases to ~ 170 K from ~ 100 K of H3LiIr2O6. Nevertheless, the quantum liquid state is robust against the deuterium isotope exchange in contrast to the theoretical prediction that the Kitaev spin liquid is stable only for a limited phase space of magnetic interactions. The bond- and site disorders associated with disordered OD(H) bonds, in combination with Kitaev physics, may play a role in realizing the quantum liquid state.journal articl

Diurnal regulation of SOS pathway and sodium excretion underlying salinity tolerance of Vigna marina

Vigna marina (Barm.) Merr. is adapted to tropical marine beaches and has an outstanding tolerance to salt stress. Given there are growing demands for cultivating crops in saline soil or with saline water, it is important to understand how halophytic species are adapted to the saline environments. Here we revealed by positron emitting tracer imaging system (PETIS) that V. marina actively excretes sodium from the root during the light period but not in the dark period. The following whole genome sequencing accompanied with forward genetic study identified a QTL region harboring SOS1, encoding plasma membrane Na+/H+ antiporter, which was associated with not only salt tolerance but also ability of sodium excretion. We also found the QTL region contained a large structural rearrangement that suppressed recombination across ~20 Mbp, fixing multiple gene loci potentially involved in salt tolerance. RNA-seq and promoter analyses revealed SOS1 in V. marina was highly expressed even without salt stress and its promoter shared common cis-regulatory motifs with those exhibiting similar expression profile. Interestingly, the cis-regulatory motifs seemed installed by a transposable element (TE) insertion. Though not identified by genetic analysis, the transcriptome data also revealed SOS2 transcription was under diurnal regulation, explaining the pattern of sodium excretion together with up-regulated expression of SOS1. Furthermore, we demonstrated that, under a condition of mild salt stress, the plants with the diurnally regulated SOS pathway outperformed those with the constitutively activated one.journal articl

Designer Catalyst-Enabled Regiodivergent Histone Acetylation

The “histone code,” defined by the combinatorial patterns of post-translational modifications (PTMs) on histones, plays a pivotal role in chromatin structure and gene expression. Tools for the regioselective introduction of histone PTMs in living cells are critical for dissecting the functions of these epigenetic marks. Here, we report the design and development of three regioselective catalysts that acetylate distinct lysine residues (K43, K108, and K120) on histone H2B. Using a combination of molecular dynamics simulations of catalyst-nucleosome complexes and systematic experimental optimization of catalyst structures, we identified key design principles for achieving regioselectivity. Specifically, excluding highly reactive off-target lysine residues from the catalyst effective region (CER) while maintaining proximity to a target lysine residue proved crucial. Biochemical and cellular analyses of the catalytic histone acetylation revealed that each lysine acetylation elicited unique effects on the binding affinity and activity of nucleosome-interacting molecules, as well as on transcriptional programs and cellular phenotypes. These findings establish a framework for designing regioselective histone acetylation catalysts and advance our understanding of the regulatory mechanisms underlying histone PTMs.journal articl

Electronic structure and resonant inelastic x-ray scattering in Ta2NiSe5

We study the electronic structure of Ta2NiSe5 in its low-temperature semiconducting phase, using resonant inelastic x-ray scattering (RIXS) at the Ta L3 edge. We also investigate the electronic properties of Ta2NiSe5 within the density-functional theory (DFT) using the generalized gradient approximation in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band-structure method. While ARPES, dc transport, and optical measurements indicate that Ta2NiSe5 is a small band-gap semiconductor, DFT gives a metallic nonmagnetic solution in Ta2NiSe5. To obtain the semiconducting ground state in Ta2NiSe5 we use a self-interaction-like correction procedure by introducing an orbital-dependent potential Vl into the Hamiltonian. We investigate theoretically the x-ray absorption spectroscopy and RIXS spectra at the Ni and Ta L3 edges and analyze the spectra in terms of interband transitions. We also investigate the RIXS spectra as a function of momentum transfer vector Q and incident photon energy.journal articl

単一電子をパルス利用した電子線励起による時間分解光計測

Cathodoluminescence, the light emission induced by electron beam, has been increasingly used in combination with electron microscopy for the analysis of semiconductors and the visualization of electromagnetic fields at the nanoscale for plasmonics or nanophotonics, surpassing the diffraction limit. This article introduces a time-resolved cathodoluminescence method that does not require pulsing the electron beam but utilizes individual electrons as excitation pulses within the naturally emitted electron beam for time-resolved measurements. The discussion focuses on two techniques: one using photon-photon correlations and the other based on electron-photon correlations. These approaches provide insights into the behavior of light at extremely small scales, offering valuable tools for advancing the understanding nanoscale optical phenomena as well as for quantum measurement.journal articl

Pressure-Induced Charge Amorphisation in BiNiO3

電子の秩序または無秩序は材料特性の基本であり、物質のさまざまな状態への単純な類似点も与える。結晶に類似した電荷秩序絶縁体状態は、多くの混合価数の材料で観察されている。加熱するとこの状態は融けて電荷液体相（金属）となり、多くの場合、興味深い関連した物理や機能を伴う。 今回、BiNiO3で観測された結晶材料における圧力誘起電荷アモルファス化について報告する。journal articl

Comparative study of gamma radiation tolerance between desiccation-sensitive and desiccation-tolerant tardigrades

Tardigrades are small metazoans renowned for their exceptional tolerance against various harsh environments in a dehydrated state. Some species exhibited an extraordinary tolerance against high-dose irradiation even in a hydrated state. Given that natural sources of high radiation are rare, the selective pressure to obtain such a high radiotolerance during evolution remains elusive. It has been postulated that high radiation tolerances could be derived from adaptation to dehydration, because both dehydration and radiation cause similar damage on biomolecules at least partly, e.g., DNA cleavage and oxidation of various biomolecules, and dehydration is a common environmental stress that terrestrial organisms should adapt to. Although tardigrades are known for high radiotolerance, the radiotolerance records have been reported only for desiccation-tolerant tardigrade species and nothing was known about the radio-tolerance in desiccation-sensitive tardigrade species. Hence, the relationship between desiccation-tolerance and radio-tolerance remained unexplored. To this end, we examined the radiotolerance of the desiccation-sensitive tardigrade, Grevenius myrops (formerly known as Isohypsibius myrops) in comparison to the well-characterized desiccation-tolerant tardigrade, Ramazzottius varieornatus. The median lethal dose (LD50) of G. myrops was approximately 2,240 Gy. This was much lower than those reported for desiccation tolerant eutardigrades. The effects of irradiation on the lifespan and the ovipositions were more severe in G. myrops compared to those in R. varieornatus. The present study provides the precise records on the radiotolerance of a desiccation-sensitive tardigrade and the current data supported the certain correlation between desiccation tolerance and radiotolerance at least in eutardigrades.journal articl

Development of high energy resolution crystal analyzer based on microporous ceramics for resonant inelastic X-ray scattering program at HEPS

The spherically bent X-ray crystal analyzer (SBCA) is one of the key optical elements for performing high energy resolution hard X-ray spectroscopies based on Rowland circle geometry. To meet the requirements of Resonant Inelastic X-ray Scattering (RIXS) program at High Energy Photon Source (HEPS), the fourth-generation high energy synchrotron in Beijing, China, high energy resolution crystal analyzers were fabricated. The fabrication processes of vacuum-mounted flat-diced crystal analyzers using home-designed devices with microporous ceramics are presented. The energy resolution of the vacuum-mounted crystal analyzers, for measuring Cu K-edge and Re L3-edge RIXS, are bench marked with that of the glued flat-diced crystal analyzers. The gluing and vacuum-mounted analyzers are proven to be reliable techniques for the routine production of spherical bent diced crystal analyzers with energy resolution in the order of tens of milli-electron volts, and with good focal properties and efficiency. In particular, the vacuum-mounted technique will be beneficial for the RIXS techniques to target element of interests.journal articl

Multiscale Synchrotron X-ray Scattering Study on the Interaction between Phase Evolution and Elasticity of CSH/PCE Composites Subjected to High Temperatures

さまざまな Ca/Si 比におけるケイ酸カルシウム水和物 (CSH)/ポリカルボン酸塩 (PCE) 複合材料の残留機械的特性に対する格子構造と原子間距離の熱変形の影響は明らかではない。本研究では、Ca/Si 比が0.6～1.0の範囲のCSH/PCE複合材料のマルチスケール構造変態と機械的特性の間の相関関係を、小角 X 線散乱とその場負荷印加のX線全散乱によって調べた。journal articl