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<jats:p>The topological valley transport, realized in phononic crystals, has aroused tremendous interest in these years. Many previous researches have further promoted the development of this transport phenomenon. Crucially, the bandwidth of the valley-projected edge mode has been an essential research topic. As is well known, the broadband will improve the adaptability of the acoustic edge-states, which will be more conducive to the transmission of information. Therefore, in this paper, we present a composite structure, composed of the atoms with different shapes forming a hexagonal lattice, which can achieve larger bandwidth than a single structure. Meanwhile, the results demonstrate that the topological protected edge states are also observed in our structure. Furthermore, the backscattering suppressions from associated valley-protected edge states under certain perturbations have also been investigated and demonstrated. Our work can provide a new idea for designing acoustic devices based on valley degree of freedom.</jats:p>

<jats:p>Nickel-based alloys have been considered as candidate structural materials used in generation IV nuclear reactors serving at high temperatures. In the present study, alloy 617 was irradiated with 180-keV helium ions to a fluence of 3.6 × 10<jats:sup>17</jats:sup> ions/cm<jats:sup>2</jats:sup> at room temperature. Throughout the cross-section transmission electron microscopy (TEM) image, numerous over-pressurized helium bubbles in spherical shape are observed with the actual concentration profile a little deeper than the SRIM predicted result. Post-implantation annealing was conducted at 700 °C for 2 h to investigate the bubble evolution. The long-range migration of helium bubbles occurred during the annealing process, which makes the bubbles of the peak region transform into a faceted shape as well. Then the coarsening mechanism of helium bubbles at different depths is discussed and related to the migration and coalescence (MC) mechanism. With the diffusion of nickel atoms slowed down by the alloy elements, the migration and coalescence of bubbles are suppressed in alloy 617, leading to a better helium irradiation resistance.</jats:p>

<jats:p>The worm-like AlN nanowires are fabricated by the plasma-enhanced chemical vapor deposition (PECVD) on Si substrates through using Al powder and N<jats:sub>2</jats:sub> as precursors, CaF<jats:sub>2</jats:sub> as fluxing medium, Au as catalyst, respectively. The as-grown worm-like AlN nanowires each have a polycrystalline and hexagonal wurtzite structure. Their diameters are about 300 nm, and the lengths are over 10 μm. The growth mechanism of worm-like AlN nanowires is discussed. Hydrogen plasma plays a very important role in forming the polycrystalline structure and rough surfaces of worm-like AlN nanowires. The worm-like AlN nanowires exhibit an excellent field-emission (FE) property with a low turn-on field of 4.5 V/μm at a current density of 0.01 mA/cm<jats:sup>2</jats:sup> and low threshold field of 9.9 V/μm at 1 mA/cm<jats:sup>2</jats:sup>. The emission current densities of worm-like AlN nanowires each have a good stability. The enhanced FE properties of worm-like AlN nanowires may be due to their polycrystalline and rough structure with nanosize and high aspect ratio. The excellent FE properties of worm-like AlN nanowires can be explained by a grain boundary conduction mechanism. The results demonstrate that the worm-like AlN nanowires prepared by the proposed simple and the PECVD method possesses the potential applications in photoelectric and field-emission devices.</jats:p>

<jats:p>Ba<jats:sub>2</jats:sub>IrO<jats:sub>4</jats:sub> is a sister compound of the widely investigated Sr<jats:sub>2</jats:sub>IrO<jats:sub>4</jats:sub> and has no IrO<jats:sub>6</jats:sub> octahedral rotation nor net canted antiferromagnetic moment, thus it acts as a system more similar to the high-<jats:italic>T</jats:italic> <jats:sub>c</jats:sub> cuprate. In this work, we synthesize the Ba<jats:sub>2</jats:sub>IrO<jats:sub>4</jats:sub> epitaxial films by reactive molecular beam epitaxy and study their crystalline structure and transport properties under biaxial compressive strain. High resolution scanning transmission electron microscopy and x-ray diffraction confirm the high quality of films with partial strain relaxation. Under compressive epitaxial strain, the Ba<jats:sub>2</jats:sub>IrO<jats:sub>4</jats:sub> exhibits the strain-driven enhancement of the conductivity, consistent with the band gap narrowing and the stronger hybridization of Ir-t<jats:sub>2g</jats:sub> and O-2p orbitals predicted in the first-principles calculations.</jats:p>

<jats:p>Dimerized spin-1/2 ladders exhibit a variety of phase structures, which depend on the intra-chain and inter-chain spin exchange energies as well as on the dimerization pattern of the ladder. Using the density matrix renormalization group (DMRG) algorithm, we study critical properties of the bond-alternating two-leg Heisenberg spin ladder with diagonal interaction <jats:italic>J</jats:italic> <jats:sub>×</jats:sub>. Two types of spin systems, staggered dimerized antiferromagnetic ladder and columnar dimerized ferro-antiferromagnetic couplings ladder, are investigated. To clarify the phase transition behaviors, we simultaneously analyze the string order parameter (SOP), the twisted order parameter (TOP), as well as a measurement of the quantum information analysis. Based on measuring this different observables, we establish the phase diagram accurately and give the fitting functions of the phase boundaries. In addition, the phase transition of cross-coupled spin ladder (in the absence of intrinsic dimerization) is also discussed.</jats:p>

<jats:p>The effects of wheel speeds and high-pressure hydrogen treatment on phase evolution, microstructure, and magnetocaloric properties in La<jats:sub>0.5</jats:sub>Pr<jats:sub>0.5</jats:sub>Fe<jats:sub>11.4</jats:sub>Si<jats:sub>1.6</jats:sub> melt-spun ribbons are studied in this work. The results reveal that the increase of wheel speed is beneficial to the formation of cubic NaZn<jats:sub>13</jats:sub>-type phase and the grain refinement. The optimized wheel speed for microstructural and magnetocaloric properties is 30 m/s. The largest entropy change of 18.1 J/kg⋅K at 190 K under a magnetic field change of 0 T–5 T is obtained in La<jats:sub>0.5</jats:sub>Pr<jats:sub>0.5</jats:sub>Fe<jats:sub>11.4</jats:sub>Si<jats:sub>1.6</jats:sub> ribbons melt-spun at 30 m/s. After a high-pressure hydrogen treatment of 50 MPa, the Curie temperature of the ribbons prepared at 30 m/s is adjusted to about 314 K and the large –Δ<jats:italic>S</jats:italic> <jats:sub>M</jats:sub> of 17.9 J/kg⋅K under a magnetic field change of 0 T–5 T is achieved at room temperature with almost none hysteresis loss. The small thermal and magnetic hysteresis and the large –Δ<jats:italic>S</jats:italic> <jats:sub>M</jats:sub> make the La<jats:sub>0.5</jats:sub>Pr<jats:sub>0.5</jats:sub>Fe<jats:sub>11.4</jats:sub>Si<jats:sub>1.6</jats:sub> hydride ribbons appropriate for magnetic refrigerant applications around room temperature.</jats:p>

<jats:p>Optoelectronic properties of MoSe<jats:sub>2</jats:sub> are modulated by controlled annealing in air. Characterizations by Raman spectroscopy and XPS demonstrate the introduction of oxygen defects. Considerable increase in electron and hole mobilities reveals the highly improved electron and hole transport. Furthermore, the photocurrent is enhanced by nearly four orders of magnitudes under 7 nW laser exposure after annealing. The remarkable enhancement in the photoresponse is attributed to an increase in hole trapping centers and a reduction in resistance. Furthermore, the annealed photodetector shows a fast time response on the order of 10 ms and responsivity of 3 × 10<jats:sup>4</jats:sup> A/W.</jats:p>

<jats:p>Pyrite FeS<jats:sub>2</jats:sub> exhibits an ultrahigh energy density (1671 W⋅h⋅kg<jats:sup>−1</jats:sup>, for the reaction of FeS<jats:sub>2</jats:sub> + 4Li = Fe + 2Li<jats:sub>2</jats:sub>S) in secondary lithium-ion batteries, but its poor cycling stability, huge volume expansion, the shuttle effect of polysulfides, and slow kinetic properties limit its practical application. In this work, we synthesize a composite structure material CoS on FeS<jats:sub>2</jats:sub> surface (FeS<jats:sub> <jats:italic>x</jats:italic> </jats:sub>@CoS, 1 &lt; <jats:italic>x</jats:italic> ≤ 2) by using a cobalt-containing MOF to improve its cycle stability. It is found that CoS inhibits the side reactions and adsorbs polysulfides. As a result, the modified FeS<jats:sub>2</jats:sub> shows a higher discharge capacity of 577 mA⋅h⋅g<jats:sup>−1</jats:sup> (919 W⋅h⋅kg<jats:sup>−1</jats:sup>) after 60 cycles than 484 mA⋅h⋅g<jats:sup>−1</jats:sup> (778 W⋅h⋅kg<jats:sup>−1</jats:sup>) of bare pyrite FeS<jats:sub>2</jats:sub>. This efficient strategy provides a valuable step toward the realization of high cycling stability FeS<jats:sub>2</jats:sub> cathode materials for secondary lithium-ion batteries and enriches the basic understanding of the influence of FeS<jats:sub>2</jats:sub> interfacial stability on its electrochemical performances.</jats:p>

<jats:p>Construction of optimal gate operations is significant for quantum computation. Here an efficient scheme is proposed for performing shortcut-based quantum gates on superconducting qubits in circuit quantum electrodynamics (QED). Two four-level artificial atoms of Cooper-pair box circuits, having sufficient level anharmonicity, are placed in a common quantized field of circuit QED and are driven by individual classical microwaves. Without the effect of cross resonance, one-qubit NOT gate and phase gate in a decoupled atom can be implemented using the invariant-based shortcuts to adiabaticity. With the assistance of cavity bus, a one-step SWAP gate can be obtained within a composite qubit-photon-qubit system by inversely engineering the classical drivings. We further consider the gate realizations by adjusting the microwave fields. With the accessible decoherence rates, the shortcut-based gates have high fidelities. The present strategy could offer a promising route towards fast and robust quantum computation with superconducting circuits experimentally.</jats:p>

<jats:p>The efficient production of hydrogen through electrocatalytic decomposition of water has broad prospects in modern energy equipment. However, the catalytic efficiency and durability of hydrogen evolution catalyst are still very deficient, which need to be further explored. Here in this work, we prove that introducing a graphene layer (Gr) between the molybdenum disulfide and nickel foam (Ni–F) substrate can greatly improve the catalytic performance of the hybrid. Owing to the excitation of local surface plasmon resonance (LSPR) of gold nanoparticles (NPs), the electrocatalytic hydrogen releasing activity of the MoS<jats:sub>2</jats:sub>/Gr/Ni–F heterostructure is greatly improved. This results in a significant increase in the current density of AuNPs/MoS<jats:sub>2</jats:sub>/Gr/Ni–F composite material under light irradiation and in the dark at 0.2 V (<jats:italic>versus</jats:italic> reversible hydrogen electrode (RHE)), which is much better than in MoS<jats:sub>2</jats:sub>/Gr/Ni–F composite materials. The enhancement of hydrogen release can be attributed to the injection of hot electrons into MoS<jats:sub>2</jats:sub>/Gr/Ni–F by AuNPs, which will improve the electron density of MoS<jats:sub>2</jats:sub>/Gr/Ni–F, promote the reduction of H<jats:sub>2</jats:sub>O, and further reduce the activation energy of the electrocatalyst hydrogen evolution reaction (HER). We also prove that the introduction of graphene can improve its stability in acidic catalytic environments. This work provides a new way of designing efficient water splitting system.</jats:p>