Databases of 2D material-substrate interfaces and 2D charged building blocks

Discovery of materials using“bottom-up”or“top-down”approach is of great interest in materials science.Layered materials consisting of two-dimensional(2D)building blocks provide a good platform to explore new materials in this respect.In van der Waals(vdW)layered materials,these building blocks are charge neutral and can be isolated from their bulk phase(top-down),but usually grow on substrate.In ionic layered materials,they are charged and usually cannot exist independently but can serve as motifs to construct new materials(bottom-up).In this paper,we introduce our recently constructed databases for 2D material-substrate interface(2DMSI),and 2D charged building blocks.For 2DMSI database,we systematically build a workflow to predict appropriate substrates and their geometries at substrates,and construct the 2DMSI database.For the 2D charged building block database,1208 entries from bulk material database are identified.Information of crystal structure,valence state,source,dimension and so on is provided for each entry with a json format.We also show its application in designing and searching for new functional layered materials.The 2DMSI database,building block database,and designed layered materials are available in Science Data Bank at https://doi.org/10.57760/sciencedb.j00113.00188.

Distinct behavior of electronic structure under uniaxial strain in BaFe_(2)As_(2)

We report a study of the electronic structure of BaFe_(2)As_(2) under uniaxial strains using angle-resolved photoemission spectroscopy and transport measurements. Two electron bands at the MY point, with an energy splitting of 50 meV in the strain-free sample, shift downward and merge into each other under a large uniaxial strain, while three hole bands at theГ point shift downward together. However, we also observed an enhancement of the resistance anisotropy under uniaxial strains by electrical transport measurements, implying that the applied strains strengthen the electronic nematic order in BaFe_(2)As_(2). These observations suggest that the splitting of these two electron bands at the MY point is not caused by the nematic order in BaFe_(2)As_(2).

Normal and Superconducting Properties of La_(3)Ni_(2)O_(7)

This review provides a comprehensive overview of current research on the structural,electronic,and magnetic characteristics of the recently discovered high-temperature superconductor La_(3)Ni_(2)O_(7) under high pressures.We present the experimental results for synthesizing and characterizing this material,derived from measurements of transport,thermodynamics,and various spectroscopic techniques,and discuss their physical implications.We also explore theoretical models proposed to describe the electronic structures and superconducting pairing symmetry in La_(3)Ni_(2)O_(7),highlighting the intricate interplay between electronic correlations and magnetic interactions.Despite these advances,challenges remain in growing high-quality samples free of extrinsic phases and oxygen deficiencies and in developing reliable measurement tools for determining diamagnetism and other physical quantities under high pressures.Further investigations in these areas are essential to deepening our understanding of the physical properties of La_(3)Ni_(2)O_(7) and unlocking its superconducting pairing mechanism.

Review of the Low-Lying Excited Baryons∑*(1/2-)

Strong empirical and phenomenological indications exist for large sea-quark admixtures in the low-lying excited baryons.Investigating the low-lying excited baryon∑*(1/2-)is important for determining the nature of the low-lying excited baryons.We review the experimental and theoretical progress on the studies of the∑*(1/2-).

Realizations, Characterizations, and Manipulations of Two-Dimensional Electron Systems Floating above Superfluid Helium Surfaces

Electron systems in low dimensions are enriched with many superior properties for both fundamental research and technical developments. Wide tunability of electron density, high mobility of motion, and feasible controllability in microscales are the most prominent advantages that researchers strive for. Nevertheless, it is always difficult to fulfill all in one solid-state system. Two-dimensional electron systems(2DESs) floating above the superfluid helium surfaces are thought to meet these three requirements simultaneously, ensured by the atomic smoothness of surfaces and the electric neutrality of helium. Here we report our recent work in preparing, characterizing, and manipulating 2DESs on superfluid helium. We realized a tunability of electron density over one order of magnitude and tuned their transport properties by varying electron distribution and measurement frequency. The work we engage in is crucial for advancing research in many-body physics and for development of single-electron quantum devices rooted in these electron systems.

Fabrication of 4-Inch Nano Patterned Wafer with High Uniformity by Laser Interference Lithography

We report the fabrication of 4-inch nano patterned wafer by two-beam laser interference lithography and analyze the uniformity in detail. The profile of the dots array with a period of 800 nm divided into five regions is characterized by a scanning electron microscope. The average size in each region ranges from 270 nm to 320 nm,and the deviation is almost 4%, which is approaching the applicable value of 3% in the industrial process. We simulate the two-beam laser interference lithography system with MATLAB software and then calculate the distribution of light intensity around the 4 inch area. The experimental data fit very well with the calculated results. Analysis of the experimental data and calculated data indicates that laser beam quality and space filter play important roles in achieving a periodical nanoscale pattern with high uniformity and large area. There is the potential to obtain more practical applications.

Monogamy and polygamy relations of multiqubit entanglement based on unified entropy

Monogamy relation is one of the essential properties of quantum entanglement,which characterizes the distribution of entanglement in a multipartite system.By virtual of the unified-(q,s) entropy,we obtain some novel monogamy and polygamy inequalities in general class of entanglement measures.For the multiqubit system,a class of tighter monogamy relations are established in term of the a-th power of unified-(q,s) entanglement for a> 1.We also obtain a class of tighter polygamy relations in the β-th(0≤β≤1) power of unified-(q,s) entanglement of assistance.Applying these results to specific quantum correlations,e.g.,entanglement of formation,Renyi-q entanglement of assistance,and Tsallisq entanglement of assistance,we obtain the corresponding monogamy and polygamy relations.Typical examples are presented for illustration.Furthermore,the complementary monogamy and polygamy relations are investigated for theα-th(0≤α≤1) and β-th(β≥1) powers of unified entropy,respectively,and the corresponding monogamy and polygamy inequalities are obtained.

Expansion dynamics of a spherical Bose–Einstein condensate

We experimentally and theoretically observe the expansion behaviors of a spherical Bose-Einstein condensate. A rubidium condensate is produced in an isotropic optical dipole trap with an asphericity of 0.037. We measure the variation of the condensate size in the expansion process after switching off the trap. The free expansion of the condensate is isotropic,which is different from that of the condensate usually produced in the anisotropic trap. We derive an analytic solution of the expansion behavior based on the spherical symmetry, allowing a quantitative comparison with the experimental measurement. The interaction energy of the condensate is gradually converted into the kinetic energy during the expansion and after a long time the kinetic energy saturates at a constant value. We obtain the interaction energy of the condensate in the trap by probing the long-time expansion velocity, which agrees with the theoretical calculation. This work paves a way to explore novel quantum states of ultracold gases with the spherical symmetry.

Mechano-chemical selections of two competitive unfolding pathways of a single DNA i-motif

The DNA i-motif is a quadruplex structure formed in tandem cytosine-rich sequences in slightly acidic conditions. Besides being considered as a building block of DNA nano-devices, it may also play potential roles in regulating chromo- some stability and gene transcriptions. The stability of i-motif is crucial for these functions. In this work, we investigated the mechanical stability of a single i-motif formed in the human telomeric sequence 51-（CCCTAA）3CCC, which revealed a novel pH and loading rate-dependent bimodal unfolding force distribution. Although the cause of the bimodal unfolding force species is not clear, we proposed a phenomenological model involving a direct unfolding favored at lower loading rate or higher pH value, which is subject to competition with another unfolding pathway through a mechanically stable inter- mediate state whose nature is yet to be determined. Overall, the unique mechano-chemical responses of i-motif-provide a new perspective to its stability, which may be useful to guide designing new i-motif-based DNA mechanical nano-devices.

Regular Arrangement of Two-Dimensional Clusters of Blue Phosphorene on Ag(111)

Two-dimensional(2D)blue phosphorene with a honeycomb structure is the phosphorus analog of graphene,and is regarded as a promising 2D material with a large tunable band gap and high charge-carrier mobility.Here,using the molecular beam epitaxy method,we synthesize monolayer blue phosphorene on the Ag(111)surface.Combined with first-principles calculations,scanning tunneling microscopy measurements reveal that the blue phosphorene on the Ag(111)surface consists of 2D clusters with a buckling 1×1 lattice,arranged regularly on the Ag(111).The formation of these phosphorus clusters stems from the strain modulation induced by the lattice mismatch between blue phosphorene and the Ag(111)substrate.Moreover,x-ray photoelectron spectroscopy measurements are performed to study the instability of the blue phosphorene clusters in air.The realization of regular nanoclusters of blue phosphorene with unique sizes and morphology provides an ideal platform for the exploration of the quantum physical properties and applications of blue phosphorene.

Properties of color-flavor locked strange quark matter in an external strong magnetic field

The properties of color-flavor locked strange quark matter in an external strong magnetic field are investigated in a quark model with density-dependent quark masses.Parameters are determined by stability arguments.It is found that the minimum energy per baryon of the color-flavor locked(MCFL)matter decreases with increasing magnetic-field strength in a certain range,which makes MCFL matter more stable than other phases within a proper magnitude of the external magnetic field.However,if the energy of the field itself is added,the total energy per baryon will increase.

Effects of chemical pressure on diluted magneticsemiconductor(Ba,K)(Zn,Mn)_2As_2

Chemical pressure induced by iso-valent doping has been widely employed to tune physical properties of materials. In this work, we report effects of chemical pressure by substitution of Sb or P into As on a recently discovered diluted magnetic semiconductor(Ba,K)(Zn,Mn)_2 As_2, which has the record of reliable Curie temperature of 230 K due to independent charge and spin doping. Sb and P are substituted into As-site to produce negative and positive chemical pressures, respectively.X-ray diffraction results demonstrate the successful chemical solution of dopants. Magnetic properties of both K-underdoped and K-optimal-doped samples are effectively tuned by Sb-and P-doping. The Hall effect measurements do not show decrease in carrier concentrations upon Sb-and P-doping. Impressively, magnetoresistance is significantly improved from7% to 27% by only 10% P-doping, successfully extending potential application of(Ba,K)(Zn,Mn)_2 As_2.

Analytical treatment of Anderson localization in a chain of trapped ions experiencing laser Bessel beams

Trapped ions, under electromagnetic confinement and Coulomb repulsion, can behave as non-interacting particles in one-dimensional lattices. Here we explore analytically the possible effects regarding Anderson localization in a chain of trapped ions experiencing laser Bessel beams. Under an experimentally feasible condition, we predict an analytical form of the energy-dependent mobility edges, which is verified to be in good agreement with the exact numerical results except for the top band. Some other important properties regarding the phonon localization in the ion chain are also discussed both analytically and numerically. Our results are relevant to experimental observation of localization–delocalization transition in the ion trap and helpful for deeper understanding of the rich phenomena due to long-range phonon hopping.

Molecular Dynamics Study on the Diffusion Properties of Hydrogen Atoms in Bulk Tungsten

Molecular dynamics simulations were performed to study the diffusion behavior of hydrogen atoms in body-centered cubic（bcc） tungsten（W）. The energy distribution of a single hydrogen atom in the （001） plane of tungsten lattice was computed. The values of diffusion barriers agree well with other theoretical and experimental results. The interaction between an H atom and a vacancy was simulated, which shows effect on the diffusion behavior of hydrogen an H atom to diffuse in bulk W with and evidence of strong binding effect. The temperature atoms was investigated. The critical temperature for without vacancies were calculated to be 950 K and 450 K, respectively, which is supported by several experimental results. In addition, the diffusion coefficient of hydrogen atoms in tungsten was evaluated and analyzed.

Synthesis, structure, and properties of Ba9Co3Se(15) with one-dimensional spin chains

A new compound with one-dimensional spin chains, Ba9Co3Se(15), was synthesized under high pressure and high temperature conditions and systematically characterized via structural, transport and magnetic measurements. Ba9Co3Se(15) crystallizes in a hexagonal structure with the space group P-6c2(No. 188) and lattice constants of a = b = 9.6765 ? and c = 18.9562 ?. The structure consists of trimeric face-sharing octahedral CoSe6 chains, which are arranged in a triangular lattice in the ab-plane and separated by Ba atoms. The distance of the nearest neighbor of CoSe6 chains is very large, given by the lattice constant a = 9.6765 ?. The Weiss temperature Tθ associated with the intra-chain coupling strength is about -346 K. However, no long-range magnetic order but a spin glass transition at ~ 3 K has been observed. Our results indicate that the spin glass behavior in Ba9Co3Se(15) mainly arises from the magnetic frustration due to the geometrically frustrated triangular lattice.

Instability in Three-Dimensional Magnetohydrodynamic Flows of an Electrically Conducting Fluid

The three-dimensional instability of an electrically conducting fluid between two parallel plates affected by an imposed transversal magnetic field is numerically investigated by a Chebyshev collocation method. The QZ method is utilized to obtain neutral curves of the linear instability. The details of instability are analyzed by solving the generalized Orr-Sommerfeld equation. The critical Reynolds number Rec, the stream-wise and span-wise critical wave numbers αc and βc are obtained for a wide range of Hartmann number Ha. The effects of Lorentz force and span-wise perturbation on three-dimensional instability are investigated. The results show that magnetic field would suppress the instability and critical Reynolds number tends to be larger than that for two-dimensional instability.

Symmetry Breaking and Reversible Hydrogenation of Two-Dimensional Semiconductor Sn2Bi

The hydrogenation of two-dimensional(2D)systems can efficiently modify the physical and chemical properties of materials.Here we report a systematic study on the hydrogenation of 2D semiconductor Sn2Bi on Si(111)by scanning tunneling microscopy experiments and first principle calculations.The unique butterfly-like and trench-like features were observed for single H adsorption sites and hydrogen-saturated surfaces respectively,from which the bridge-site adsorption geometry can be unambiguously determined.The structural model was further confirmed by the theoretical calculations,which is in good agreement with the experimental observation.In addition,the hydrogenation is found to vanish the flat band of Sn2Bi and increase the band gap obviously.

Coulombic interaction in the colloidal oriented-attachment growth of tetragonal nanorods

In this report, the analytical expression of Coulombic interaction between a spherical nanoparticle and a tetragonal nanorod is derived. To evaluate the Coulombic interaction in the oriented attachment growth of tetragonal nanorods, we analyze the correlation between the Coulombic interaction and the important growth parameters, including： nanoparticle- nanorod separation, aspect ratio of the nanorods, and surface charge density. Our work opens up the opportunity to investi-gate interparticle interactions in the oriented attachment growth of tetragonal nanorods.

Ultra-High Efficiency Magnetic Transport of SZRb Atoms in a Single Chamber Bose-Einstein Condensation Apparatus

We report the ultra-high efficiency transport of cold ST Ftb atoms using a moving magnetic quadrupole potential generated by three overlapping pairs of fixed coils. The transfer etticiency is better than 97%, which is the highest ever reported to our knowledge. The temperature increase due to heating is less than IO #K when the initial cloud temperature is llO#K. Our setup is similar to the magnetic transferring belt design [Phys. ftev. A 63 （2001）031401（R）], although it is simpler because the push coil is not required. We use it to transport atoms away from a magneto-optical trap to very close to the wall of the glass cell, facilitating future experiments employing three-dimensional optical lattices, high resolution in-situ imaging, and magnetic Feshbach resonances.

Coexistence of Polaronic States and Superconductivity in Iron-Pnictide Compound Ba_2Ti_2Fe_2As_4O

The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show a‘peak-dip-hump＇ line shape with two branches of dispersion associated with the polaronic states at temperatures below around 120 K. This change in the spectra occurs along with the resistivity anomaly that was not clearly understood in a previous study. Moreover, an energy gap induced by the superconducting proximity effect opens in the polaronic bands at temperatures below T_c（~21 K）. Our study provides the spectroscopic evidence that superconductivity coexists with polarons in the same bands near the Fermi level, which provides a suitable platform to study interactions between charge, lattice and spin freedoms in a correlated system.