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<jats:p>A minimal cellular automaton model is introduced to describe the collective motion of self-propelled particles on two-dimensional square lattice. The model features discretization of directional and positional spaces and single-particle occupation on one lattice site. Contrary to the Vicsek model and its variants, our model exhibits the nonvanishing optimal noise. When the particle density increases, the collective motion is promoted with optimal noise strength and reduced with noise strength out of optimal region. In addition, when the square lattice undergoes edge percolation process, no abrupt change of alignment behaviors is observed at the critical point of percolation.</jats:p>

<jats:p>Nanoclusters consisting of a few atoms have attracted a lot of research interests due to their exotic size-dependent properties. Here, well-ordered two-dimensional Sb cluster superlattice was fabricated on Si substrate by a two-step method and characterized by scanning tunneling microscopy. High resolution scanning tunneling microscope measurements revealed the fine structures of the Sb clusters, which consist of several Sb atoms ranging from 2 to 7. Furthermore, the electronic structure of the nanocluster displays the quantized energy-level which is due to the single-electron tunneling effects. We believe that the fabrication of Sb cluster superlattice broadens the species of the cluster superlattice and provides a promising candidate to further explore the novel physical and chemical properties of the semimetal nanocluster.</jats:p>

<jats:p>Oxidation corrosion of steels usually occurs in contact with the oxygen-contained environment, which is accelerated by high oxygen concentration and irradiation. The oxidation mechanism of steels is investigated by the adsorption/solution of oxygen atoms on/under body-centered-cubic (bcc) iron surfaces, and diffusion of oxygen atoms on the surface and in the near-surface region. Energetic results indicate that oxygen atoms prefer to adsorb at hollow and long-bridge positions on the Fe(100) and (110) surfaces, respectively. As the coverage of oxygen atoms increases, oxygen atoms would repel each other and gradually dissolve in the near-surface and bulk region. As vacancies exist, oxygen atoms are attracted by vacancies, especially in the near-surface and bulk region. Dynamic results indicate that the diffusion of O atoms on surfaces is easier than that into near-surface, which is affected by oxygen coverage and vacancies. Moreover, the effects of oxygen concentration and irradiation on oxygen density in the near-surface and bulk region are estimated by the McLean’s model with a simple hypothesis.</jats:p>

<jats:p>Reducing the Schottky barrier height (SBH) and even achieving the transition from Schottky contacts to Ohmic contacts are key challenges of achieving high energy efficiency and high-performance power devices. In this paper, the modulation effects of biaxial strain on the electronic properties and Schottky barrier of MoSi<jats:sub>2</jats:sub>N<jats:sub>4</jats:sub> (MSN)/graphene and WSi<jats:sub>2</jats:sub>N<jats:sub>4</jats:sub> (WSN)/graphene heterojunctions are examined by using first principles calculations. After the construction of heterojunctions, the electronic structures of MSN, WSN, and graphene are well preserved. Herein, we show that by applying suitable external strain to a heterojunction stacked by MSN or WSN — an emerging two-dimensional (2D) semiconductor family with excellent mechanical properties — and graphene, the heterojunction can be transformed from Schottky p-type contacts into n-type contacts, even highly efficient Ohmic contacts, making it of critical importance to unleash the tremendous potentials of graphene-based van der Waals (vdW) heterojunctions. Not only are these findings invaluable for designing high-performance graphene-based electronic devices, but also they provide an effective route to realizing dynamic switching either between n-type and p-type Schottky contacts, or between Schottky contacts and Ohmic contacts.</jats:p>

<jats:p>The hybridization between the localized 4f level (f) with conduction (c) electrons in <jats:italic>γ</jats:italic>-Ce upon cooling has been previously revealed in single crystalline thin films experimentally and theoretically, whereas its influence on the <jats:italic>γ</jats:italic> → <jats:italic>α</jats:italic> phase transition was not explicitly verified, due to the fact that the phase transition happened in the bulk-layer, leaving the surface in the <jats:italic>γ</jats:italic> phase. Here in our work, we circumvent this issue by investigating the effect of alloying addition of La on Ce, by means of crystal structure, electronic transport and angle resolved photoemission spectroscopy measurements, together with a phenomenological periodic Anderson model and a modified Anderson impurity model. Our current researches indicate that the weakening of f–c hybridization is the major factor in the suppression of <jats:italic>γ</jats:italic> → <jats:italic>α</jats:italic> phase transition by La doping. The consistency of our results with the effects of other rare earth and actinide alloying additions on the <jats:italic>γ</jats:italic> → <jats:italic>α</jats:italic> phase transition of Ce is also discussed. Our work demonstrates the importance of the interaction between f and c electrons in understanding the unconventional phase transition in Ce, which is intuitive for further researches on other rare earth and actinide metals and alloys with similar phase transition behaviors.</jats:p>

<jats:p>Two-dimensional (2D) moiré materials have attracted a lot of attention and opened a new research frontier of twistronics due to their novel physical properties. Although great progress has been achieved, the inability to precisely and reproducibly manipulate the twist angle hinders the further development of twistronics. Here, we demonstrated an atomic force microscope (AFM) tip manipulation method to control the interlayer twist angle of epitaxial MoS<jats:sub>2</jats:sub>/graphene heterostructure with an ultra-high accuracy better than 0.1°. Furthermore, conductive AFM and spectroscopic characterizations were conducted to show the effects of the twist angle on moiré pattern wavelength, phonons and excitons. Our work provides a technique to precisely control the twist angle of 2D moiré materials, enabling the possibility to establish the phase diagrams of moiré physics with twist angle.</jats:p>

<jats:p>The pseudogap state is one of the most enigmatic characteristics in the anomalous normal state properties of the high temperature cuprate superconductors. A central issue is to reveal whether there is a symmetry breaking and which symmetries are broken across the pseudogap transition. By performing high resolution laser-based angle-resolved photoemission measurements on the optimally-doped Bi<jats:sub>2</jats:sub>Sr<jats:sub>1.6</jats:sub>La<jats:sub>0.4</jats:sub>CuO<jats:sub>6+<jats:italic>δ</jats:italic> </jats:sub> superconductor, we report the observations of the particle–hole symmetry conservation in both the superconducting state and the pseudogap state along the entire Fermi surface. These results provide key insights in understanding the nature of the pseudogap and its relation with high temperature superconductivity.</jats:p>

<jats:p>The magnetic properties of single crystals Si, SrTiO<jats:sub>3</jats:sub>, LaAlO<jats:sub>3</jats:sub>, MgO, and (La,Sr)(Al,Ta)O<jats:sub>3</jats:sub> were investigated systematically. Three origins of the magnetizations of these crystals, namely, an intrinsic diamagnetic, a paramagnetic, and a ferromagnetic contribution, have been found to influence the magnetic signals measured on the crystals, in some important application scenarios such crystals being served as substrates with the magnetic thin film epitaxially grown on. Quantitative analyses methodologies were developed and thorough investigations were performed on the crystals with the intrinsic materials parameters thus revealed, especially that the intrinsic diamagnetic susceptibility differential d<jats:italic>χ</jats:italic> <jats:sub>dia</jats:sub>/d<jats:italic>T</jats:italic> were identified quantitatively for the first time in SrTiO<jats:sub>3</jats:sub>, LaAlO<jats:sub>3</jats:sub>, MgO, and (La,Sr)(Al,Ta)O<jats:sub>3</jats:sub>. The paramagnetic contribution is found to be the key in terms of the magnetic properties of the crystals, which in turn is in fact a consequence of the 3d impurities doping inside the crystal. All the intrinsic materials parameters are given in this paper as datasets, the datasets are openly available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://www.doi.org/10.57760/sciencedb.j00113.00028" xlink:type="simple">https://www.doi.org/10.57760/sciencedb.j00113.00028</jats:ext-link>.</jats:p>

<jats:p>Using an effective field theory with correlations, magnetic properties of an octahedral chain described by a mixed spin Ising model are investigated. Unique phenomena such as multiple hysteresis loops, saturation magnetization, and reverse flip of the magnetization plateaus occur when certain typical parameters are applied. These results may be helpful to further investigate the magnetic properties of one-dimensional systems and could potentially be utilized in the design of spin devices.</jats:p>

<jats:p>The high-performance electromagnetic (EM) wave absorption material Ba(CoTi)<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Fe<jats:sub>12–2<jats:italic>x</jats:italic> </jats:sub>O<jats:sub>19</jats:sub>@BiFeO<jats:sub>3</jats:sub> was prepared by solid-state reaction, and its EM wave absorption properties were deeply studied. The results revealed that Ba(CoTi)<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Fe<jats:sub>12–2<jats:italic>x</jats:italic> </jats:sub>O<jats:sub>19</jats:sub>@BiFeO<jats:sub>3</jats:sub> could obtain excellent absorption properties in hundreds of megahertz by adjusting the Co<jats:sup>2+</jats:sup>–Ti<jats:sup>4+</jats:sup> content. The best comprehensive property was obtained for <jats:italic>x</jats:italic> = 1.2, where the optimal reflection loss (<jats:italic>RL</jats:italic>) value reaches –30.42 dB at about 600 MHz with thickness of 3.5 mm, and the corresponding effective absorption band covers the frequency range of 437 MHz–1 GHz. Moreover, the EM wave absorption mechanism was studied based on the simulation methods. The simulated results showed that the excellent EM wave absorption properties of Ba(CoTi)<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Fe<jats:sub>12–2<jats:italic>x</jats:italic> </jats:sub>O<jats:sub>19</jats:sub>@BiFeO<jats:sub>3</jats:sub> mainly originated from the internal loss caused by natural resonance, and the interface cancelation further improved the absorption properties and resulted in <jats:italic>RL</jats:italic> peaks.</jats:p>