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<jats:p>The synchronization of the spin Hall nano-oscillator (SHNO) device driven by the pure spin current has been investigated with micromagnetic simulations. It was found that the power spectra of nanowire-based SHNO devices can be synchronized by varying the current flowing in the heavy metal (HM) layer. The synchronized signals have relatively high power and narrow linewidth, favoring the potential applications. We also found that the synchronized spectra are strongly dependent on both the number and length of nanowires. Moreover, a periodic modulation of power spectra can be obtained by introducing interfacial Dzyaloshinskii–Moriya interaction (iDMI). Our findings could enrich the current understanding of spin dynamics driven by the pure spin current. Further, it could help to design novel spintronic devices.</jats:p>

<jats:p>Since defects such as traps and oxygen vacancies exist in dielectrics, it is difficult to fabricate a high-performance MoS<jats:sub>2</jats:sub> field-effect transistor (FET) using atomic layer deposition (ALD) Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> as the gate dielectric layer. In this paper, NH<jats:sub>3</jats:sub> <jats:italic>in situ</jats:italic> doping, a process treatment approach during ALD growth of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>, is used to decrease these defects for better device characteristics. MoS<jats:sub>2</jats:sub> FET has been well fabricated with this technique and the effect of different NH<jats:sub>3</jats:sub> <jats:italic>in situ</jats:italic> doping sequences in the growth cycle has been investigated in detail. Compared with counterparts, those devices with NH<jats:sub>3</jats:sub> <jats:italic>in situ</jats:italic> doping demonstrate obvious performance enhancements: <jats:italic>I</jats:italic> <jats:sub>on</jats:sub>/<jats:italic>I</jats:italic> <jats:sub>off</jats:sub> is improved by one order of magnitude, from 1.33 × 10<jats:sup>5</jats:sup> to 3.56 × 10<jats:sup>6</jats:sup>, the threshold voltage shifts from –0.74 V to –0.12 V and a small subthreshold swing of 105 mV/dec is achieved. The improved MoS<jats:sub>2</jats:sub> FET performance is attributed to nitrogen doping by the introduction of NH<jats:sub>3</jats:sub> during the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> ALD growth process, which leads to a reduction in the surface roughness of the dielectric layer and the repair of oxygen vacancies in the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> layer. Furthermore, the MoS<jats:sub>2</jats:sub> FET processed by <jats:italic>in situ</jats:italic> NH<jats:sub>3</jats:sub> doping after the Al and O precursor filling cycles demonstrates the best performance; this may be because the final NH<jats:sub>3</jats:sub> doping after film growth restores more oxygen vacancies to screen more charge scattering in the MoS<jats:sub>2</jats:sub> channel. The reported method provides a promising way to reduce charge scattering in carrier transport for high-performance MoS<jats:sub>2</jats:sub> devices.</jats:p>

<jats:p>Near-IR (wavelength ≈ 1 μm) laser ablation of bulk, chemically-inert gold in water was compared for different laser pulse width in broad the range of 300 fs–100 ns, comparing a number of key ablation characteristics: mass loss, single-shot crater volume and extinction coefficient of the generated colloidal solutions taken in the spectral ranges of interband transitions and localized plasmon resonance. Comparing to related air-based ablation results, at the given fluences laser ablation in the liquid resulted in the maximum ablation yield per unit energy and maximum NP yield per pulse and per unit energy for the picosecond lasers, occurring at subcritical peak pulse powers for laser self-focusing. The self-focusing effect was demonstrated to yield in incomplete, effectively weaker focusing in the water filaments of ultrashort laser pulses with supercritical peak powers, comparing to linear (geometrical) focusing at sub-critical peak powers. At the other, nanosecond-pulse extreme the high ablation yield per pulse, but low ablation yield per unit energy and low NP yield per pulse and per unit energy were related to strong ablation plasma screening, providing mass removal according to the well-established scaling relationships for plasma. Illustrative comparison of the ablation and nanoparticle generation efficiency versus the broad fs–ns laser pulse width range was enabled in terms of productivity, economicity, and ergonomicity, using the proposed universal quantitative criteria.</jats:p>

<jats:p>Non-stoichiometric copper selenide (Cu<jats:sub>2 – <jats:italic>x</jats:italic> </jats:sub>Se, <jats:italic>x</jats:italic> = 0.18 ∼ 0.25) nanomaterials have attracted extensive attentions due to their excellent thermoelectric, optoelectronic and photocatalytic performances. However, efficient production of Cu<jats:sub>2 – <jats:italic>x</jats:italic> </jats:sub>Se nanoparticles (NPs) through a green and convenient way is still hindered by the inevitable non-environmentally friendly operations in common chemical synthesis. Herein, we initially reveal the coexistence of seleninic acid content and elemental selenium (Se) NPs in pulsed laser-generated Se colloidal solution. Consequently, we put forward firstly a closed-cycle reaction mode for totally green production of Cu<jats:sub>1.8</jats:sub>Se NPs to exclude traditional requirements of high temperature and toxic precursors by using Se colloidal solution. In such closed-cycle reaction, seleninic acid works as the initiator to oxidize copper sheet to release cuprous ions which can catalyze the disproportion of Se NPs to form <jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{SeO}}}_{3}^{2-}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">SeO</mml:mi> </mml:mrow> <mml:mn>3</mml:mn> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>−</mml:mo> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_31_7_078102_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and Se<jats:sup>2–</jats:sup> ions and further produce Cu<jats:sub>2 – <jats:italic>x</jats:italic> </jats:sub>Se NPs, and the by-product <jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{SeO}}}_{3}^{2-}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">SeO</mml:mi> </mml:mrow> <mml:mn>3</mml:mn> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>−</mml:mo> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_31_7_078102_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> ions promote subsequent formation of cuprous from the excessive Cu sheet. In experiments, the adequate copper (Cu) sheet was simply dipped into such Se colloidal solution at 70 °C, and then the stream of Cu<jats:sub>1.8</jats:sub>Se NPs could be produced until the exhaustion of selenium source. The conversion rate of Se element reaches to more than 75% when the size of Se NPs in weakly acidic colloidal solution is limited between 1 nm and 50 nm. The laser irradiation duration shows negative correlation with the size of Se NPs and unobvious impact to the pH of the solution which both are essential to the high yield of Cu<jats:sub>1.8</jats:sub>Se NPs. Before Cu sheet is exhausted, Se colloidal solution can be successively added without influences to the product quality and the Se conversion rate. Such green methodology positively showcases a brand-new and potential strategy for mass production of Cu<jats:sub>2 – <jats:italic>x</jats:italic> </jats:sub>Se nanomaterials.</jats:p>

<jats:p>A machine learning (ML) potential for Au clusters is developed through training on a dataset including several different sized clusters. This ML potential accurately covers the whole configuration space of Au clusters in a broad size range, thus expressing a good performance in search of their global minimum energy structures. Based on our potential, the low-lying structures of 17 different sized Au clusters are identified, which shows that small sized Au clusters tend to form planar structures while large ones are more likely to be stereo, revealing the critical size for the two-dimensional (2D) to three-dimensional (3D) structural transition. Our calculations demonstrate that ML is indeed powerful in describing the interaction of Au atoms and provides a new paradigm on accelerating the search of structures.</jats:p>

<jats:p>Multifunctional luminescent materials are attracting attention nowadays. In this work, monoclinic Gd<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>:Er<jats:sup>3+</jats:sup> nanoparticles, which possess up-conversion luminescence and down-conversion luminescence properties, were successfully synthesized by laser ablation in liquid (LAL) technique. Up-conversion luminescence and down-conversion luminescence of monoclinic Gd<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>:Er<jats:sup>3+</jats:sup> nanoparticles were got under the excitation of 980 nm and 379 nm, respectively. In addition, tunable luminescence was got. Furthermore, the cytotoxicity of the nanoparticles is low and the fluorescence of the nanoparticles in cell is also strong enough. The results indicate that the Gd<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>:Er<jats:sup>3+</jats:sup> nanoparticles synthesized by LAL technique are promising candidates for bio-imaging or other fields that require controllable fluorescence.</jats:p>

<jats:p>Memristive neural network has attracted tremendous attention since the memristor array can perform parallel multiply-accumulate calculation (MAC) operations and memory-computation operations as compared with digital CMOS hardware systems. However, owing to the variability of the memristor, the implementation of high-precision neural network in memristive computation units is still difficult. Existing learning algorithms for memristive artificial neural network (ANN) is unable to achieve the performance comparable to high-precision by using CMOS-based system. Here, we propose an algorithm based on off-chip learning for memristive ANN in low precision. Training the ANN in the high-precision in digital CPUs and then quantifying the weight of the network to low precision, the quantified weights are mapped to the memristor arrays based on VTEAM model through using the pulse coding weight-mapping rule. In this work, we execute the inference of trained 5-layers convolution neural network on the memristor arrays and achieve an accuracy close to the inference in the case of high precision (64-bit). Compared with other algorithms-based off-chip learning, the algorithm proposed in the present study can easily implement the mapping process and less influence of the device variability. Our result provides an effective approach to implementing the ANN on the memristive hardware platform.</jats:p>

<jats:p>The <jats:sup>74</jats:sup>Se is one of 35 p-nuclei, and <jats:sup>82</jats:sup>Se is a r-process only nucleus, and their (n, <jats:italic>γ</jats:italic>) cross sections are vital input parameters for nuclear astrophysics reaction network calculations. The neutron capture cross section in the resonance range of isotopes and even natural selenium samples has not been measured. Prompt <jats:italic>γ</jats:italic>-rays originating from neutron-induced capture events were detected by four C<jats:sub>6</jats:sub>D<jats:sub>6</jats:sub> liquid scintillator detectors at the Back-n facility of China Spallation Neutron Source (CSNS). The pulse height weighting technique (PHWT) was used to analyze the data in the 1 eV to 100 keV region. The deduced neutron capture cross section was compared with ENDF/B-VIII.0, JEFF-3.2, and JENDL-4.0, and some differences were found. Resonance parameters were extracted by the <jats:italic>R</jats:italic>-matrix code SAMMY in the 1 eV–1 keV region. All the cross sections of <jats:sup>nat</jats:sup>Se and resonance parameters are given in the datasets. The datasets are openly available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.doi.org/10.11922/sciencedb.j00113.00019" xlink:type="simple">http://www.doi.org/10.11922/sciencedb.j00113.00019</jats:ext-link>.</jats:p>

<jats:p>This paper is concerned with construction of quantum fields presentation and generating functions of symplectic Schur functions and symplectic universal characters. The boson–fermion correspondence for these symmetric functions have been presented. In virtue of quantum fields, we derive a series of infinite order nonlinear integrable equations, namely, universal character hierarchy, symplectic KP hierarchy and symplectic universal character hierarchy, respectively. In addition, the solutions of these integrable systems have been discussed.</jats:p>

<jats:p>Majorana zero modes (MZMs) are Majorana-fermion-like quasiparticles existing in crystals or hybrid platforms with topologically non-trivial electronic structures. They obey non-Abelian braiding statistics and are considered promising to realize topological quantum computing. Discovery of MZM in the vortices of the iron-based superconductors (IBSs) has recently fueled the Majorana research in a way which not only removes the material barrier requiring construction of complicated hybrid artificial structures, but also enables observation of pure MZMs under higher temperatures. So far, MZMs have been observed in iron-based superconductors including FeTe<jats:sub>0.55</jats:sub>Se<jats:sub>0.45</jats:sub>, (Li<jats:sub>0.84</jats:sub>Fe<jats:sub>0.16</jats:sub>)OHFeSe, CaKFe<jats:sub>4</jats:sub>As<jats:sub>4</jats:sub>, and LiFeAs. In this topical review, we present an overview of the recent STM studies on the MZMs in IBSs. We start with the observation of MZMs in the vortices in FeTe<jats:sub>0.55</jats:sub>Se<jats:sub>0.45</jats:sub> and discuss the pros and cons of FeTe<jats:sub>0.55</jats:sub>Se<jats:sub>0.45</jats:sub> compared with other platforms. We then review the following up discovery of MZMs in vortices of CaKFe<jats:sub>4</jats:sub>As<jats:sub>4</jats:sub>, impurity-assisted vortices of LiFeAs, and quantum anomalous vortices in FeTe<jats:sub>0.55</jats:sub>Se<jats:sub>0.45</jats:sub>, illustrating the pathway of the developments of MZM research in IBSs. Finally, we give perspective on future experimental works in this field.</jats:p>