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<jats:title>Abstract</jats:title> <jats:p>Unintentional nitrogen incorporation has been observed in a set of microwave plasma chemical vapor deposition (MPCVD)-grown samples. No abnormality has been detected on the apparatus especially the base pressure and feeding gas purity. By a comprehensive investigation including the analysis of the plasma composition, we have found that a minor leakage of the system could be significantly magnified by the thermal effect, resulting in a considerable residual nitrogen in the diamond material. Moreover, the doping mechanism of leaked air is different to pure nitrogen doping. The dosage of several ppm of pure nitrogen can lead to efficient nitrogen incorporation in diamond, while at least thousands ppm of leaked air is required for detecting obvious residual nitrogen. The difference of the dosage has been ascribed to the suppression effect of oxygen that consumes nitrogen. As the unintentional impurity is basically detrimental to the controllable fabrication of diamond for electronic application, we have provided an effective way to suppress the residual nitrogen in a slightly leaked system by modifying the susceptor geometry. This study indicates that even if a normal base pressure can be reached, the nitrogen residing in the chamber can be “activated” by the thermal effect and thus be incorporated in diamond material grown by a MPCVD reactor.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Lattice parameters are a basic quantity in material characterization and a slight alteration in lattice parameters directly affects the properties of materials. However, there is still considerable controversies on whether lattice expansion or contraction occurs in metallic nanomaterials with size reduction. Here, the size dependence of lattice parameter and surface free energy of clean Cu (100) films are investigated by simulations. Lattice parameters of the exposed surfaces contract whereas lattice expansion occurs along the direction perpendicular to the surfaces with decreasing film thicknesses. This is striking since the metallic bonds are usually lack of strong directionality and it is always regarded that the lattice variations in all directions are consistent. The contraction parallel to the surface is severer than the expansion perpendicular to the surface in films. Lattices changes from cubic to tetragonal with decreasing film thickness. Consequently, common contractions and occasional expansions of lattice parameters of Cu nanoparticles are observed in previous experiments. Increasing free energy and surface free energy with decreasing thicknesses is the thermodynamic origin of the lattice variations. Our study therefore provides a comprehensive physical basis for the surface effects on the lattice variations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Modulated electronic state due to the layered crystal structures brings about moderate anisotropy of superconductivity in the iron-based superconductors and thus Abrikosov vortices are expected in the mixed state. However, based on the angular and temperature dependent transport measurements in iron-based superconductor Ca<jats:sub>10</jats:sub>(Pt<jats:sub>3</jats:sub>As<jats:sub>8</jats:sub>)((Fe<jats:sub>0.9</jats:sub>Pt<jats:sub>0.1</jats:sub>)<jats:sub>2</jats:sub>As<jats:sub>2</jats:sub>)<jats:sub>5</jats:sub> with <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> &amp;#8771; 12 K, we find clear evidences of a crossover from Abrikosov vortices to Josephson vortices at a crossover temperature <jats:italic>T</jats:italic> <jats:sup>&amp;#8902;</jats:sup> &amp;#8771; 7 K, when the applied magnetic field is parallel to the superconducting FeAs layers, i.e., the angle between the magnetic field and the FeAs layers <jats:italic>θ</jats:italic> = 0°. This crossover to Josephson vortices is demonstrated by an abnormal decrease (increase) of the critical current (flux-flow resistance) below <jats:italic>T</jats:italic> <jats:sup>&amp;#8902;</jats:sup>, in contrast to the increase (decrease) of the critical current (flux-flow resistance) above <jats:italic>T</jats:italic> <jats:sup>&amp;#8902;</jats:sup> expected for Abrikosov vortices. Furthermore, when <jats:italic>θ</jats:italic> is larger than 0.5°, the flux-flow resistance and critical current have no anomalous behaviors across <jats:italic>T</jats:italic> <jats:sup>&amp;#8902;</jats:sup>. These anomalous behaviors can be understood in terms of the distinct transition from the well-pinned Abrikosov vortices to the weakly-pinned Josephson vortices upon cooling, when the coherent length perpendicular to the FeAs layers <jats:italic>ξ</jats:italic> <jats:sub>⊥</jats:sub> becomes shorter than half of the interlayer distance <jats:italic>d</jats:italic>/2. These experimental findings indicate the existence of intrinsic Josephson junctions below <jats:italic>T</jats:italic> <jats:sup>&amp;#8902;</jats:sup> and thus quasi-two-dimensional superconductivity in Ca<jats:sub>10</jats:sub>(Pt<jats:sub>3</jats:sub>As<jats:sub>8</jats:sub>)((Fe<jats:sub>0.9</jats:sub>Pt<jats:sub>0.1</jats:sub>)<jats:sub>2</jats:sub>As<jats:sub>2</jats:sub>)<jats:sub>5</jats:sub>, similar to those in the cuprate superconductors.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have extended two adaptive step size methods for solving two-dimensional or multidimensional GNLSE: one is the conservation quantity error adaptive step control method (RK4IP-CQE) and the other is the local error adaptive step control method (RK4IP-LEM). The methods are developed on the vector form fourth-order Runge-Kutta iterative scheme in the interaction picture with converting a vector equation in frequency domain. By simulating the supercontinuum generation in the high birefringence photonic crystal fiber, the calculation accuracy and the efficiency of the two adaptive step size methods are discussed. The simulation results show that the two methods suffer the same global average error, while RK4IP-LEM consumes more time than RK4IP-CQE does. The reason for the huge calculation time reduction is due to the convergences differences of the relative photon number error and the approximated local error between these two adaptive step size algorithms.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Since the evolution of a mixed state in a unitary system is equivalent to the joint evolution of the eigenvectors contained in it, we could use the tool of instantaneous angular velocity for pure states to study the quantum speed limit (QSL) of a mixed state. We derive a lower bound for the evolution time of a mixed state to a target state in a unitary system, which automatically reduces to the quantum speed limit induced by the Fubini-Study metric for pure states. The computation of the QSL of a degenerate mixed state is more complicated than that of a non-degenerate mixed state, where we have to make a singular value decomposition (SVD) on the inner product between the two eigenvector matrices of the initial and target state. By combing these results, a lower bound for the evolution time of a general mixed state is presented. In order to compare the tightness among the lower bound proposed here and lower bounds reported in the references, two examples in a single-qubit system and in a single-qutrit system are studied analytically and numerically, respectively. All conclusions derived in this work is independent of the eigenvalues of the mixed state, which is in accord with the evolution properties of a quantum unitary system.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study inserting Co layer thickness-dependent spin transport and spin-orbit torques (SOTs) in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance. The interfacial perpendicular magnetic anisotropy (IPMA) energy density (<jats:italic>K</jats:italic> <jats:sub>s</jats:sub> = 2.7 erg/cm<jats:sup>2</jats:sup>), which is dominated by interfacial spin-orbit coupling (ISOC) in the Pt/Co interface, total effective spin-mixing conductance (<jats:italic>G</jats:italic> <jats:sub>eff,tot</jats:sub> <jats:sup>↑↓</jats:sup>=0.42×<jats:sup>15</jats:sup> Ω<jats:sup>-1</jats:sup> m<jats:sup>-2</jats:sup>) and two-magnon scattering (<jats:italic>β</jats:italic> <jats:sub>TMS</jats:sub>= 0.46 nm<jats:sup>2</jats:sup>) are first characterized, and the damping-like torque (ξ<jats:sub>DL</jats:sub>= 0.103) and field-like torque (ξ<jats:sub>FL</jats:sub>=-0.017) efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer. The significant enhancement of ξ<jats:sub>DL</jats:sub> and ξ<jats:sub>FL</jats:sub> in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashba-Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface. Additionally, we find a considerable out-of-plane spin polarization SOT, which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface. Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation. Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>As a typical 2D coating material, graphene has been utilized to effectively reduce secondary electron emission from the surface. Nevertheless, the microscopic mechanism and the dominant factor of secondary electron emission suppression remain controversial. Since traditional models rely on experimental bulk properties data which is scarcely appropriate for the 2D coating situation, this paper presents a first-principles based numerical calculation of the electron interaction and emission process for monolayer and multilayer graphene on the silicon (111) substrate. By using the anisotropic energy loss for the coating graphene, the electron transport process can be described more realistically. The real physical electron interactions, including the elastic scattering of electron-nucleus, inelastic scattering of the electron-extranuclear electron and electron-phonon effect, are considered and calculated based on the Monte Carlo method. To be independent of experimental data, the energy level transition theory based first-principles method and the full Penn Algorithm are used to calculate the energy loss function during the inelastic scattering. Variations of the energy loss function and interface electron density difference for 1L to 4L layer graphene coating GoSi are calculated, and their inner electron distributions and secondary electron emission are analyzed. Simulation results demonstrate that the dominant factor of the SEY inhibition for GoSi is the mechanism by inducing electrons deeper during the internal scattering process. In contrast, a low surface potential barrier due to the positive deviation of electron density difference in monolayer GoSi interface inversely weakens the suppression of graphene layer on secondary electron emission. Only when the graphene layer number is 3L, the contribution of surface work function to the secondary electron emission suppression presents to be slightly positive.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present experimental observations of soliton pulsations in the net normal-dispersion fiber laser using the dispersive Fourier transform (DFT) technique. According to the pulsating characteristics, the soliton pulsations are classified as visible and invisible soliton pulsation. The visible soliton pulsation converted from single- to dual-soliton pulsation with the common characteristics of energy oscillation and bandwidth breathing. The invisible soliton pulsation underwent periodic variation in the spectral profile and peak power but remained invariable in pulse energy. The reason for invisible soliton pulsation behavior was periodic oscillation of the pulse inside the soliton molecule. These results could be helpful for deepening our understanding of the soliton pulsation phenomena.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in isolated system. We study the relaxation dynamics in a one-dimensional extended Bose-Hubbard model after a global interaction quench by considering several observables: the local Boson numbers, the nonlocal entanglement entropy, and the momentum distribution functions. We calculate the thermalization fidelity for the different quench parameters and the different sizes of subsystems, and the results show that the degree of thermalization is affected by the distance from the integrable point and the size of the subsystem. We employ the Pearson coefficient as the measurement of the correlation between the entanglement entropy and thermalization fidelity, and a strong correlation is demonstrated for the quenched system.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this study, the metal-insulator-metal (MIM)-based arced-shaped resonator coupled with a rectangular stub (MARS) structure is proposed. This structure can generate two tunable Fano resonances originating from two different mechanisms. The structure has the advantage of being sensitive to the refractive index, and this feature makes it favorable to be applied in various microsensors. The relationship between the structural parameters and Fano resonance is researched by the finite element method (FEM) based on the software COMSOL Multiphysics 5.4. The simulation reveals that the sensitivity reaches 1900 nm/refractive index unit (RIU), and the figure of merit (FOM) is 23.75.</jats:p>