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<jats:p>Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information. Here we experimentally demonstrate that three distinct dominated magneto-dynamic modes are excited simultaneously and coexist in a transversely magnetized ferromagnetic wire by the ferromagnetic resonance (FMR) technique. Besides the uniform FMR mode, the spin-wave well mode, the backward volume magnetostatic spin-wave mode, and the perpendicular standing spin-wave mode are experimentally observed and further confirmed with more detailed spatial profiles by micromagnetic simulation. Furthermore, our experimental approach can also access and reveal damping coefficients of these spin-wave modes, which provides essential information for development of magnonic devices in the future.</jats:p>

<jats:p>Functionalized two-dimensional materials with multiferroicity are highly desired to be next-generation electronic devices. Here we theoretically predict a family of Janus vanadium dichalcogenides VXX’ (X/X’ = S, Se, Te) monolayers with multiferroic properties, combing ferromagnetism, ferroelasticity and piezoelectricity. Due to the unpaired electrons on the V atom, the Janus VXX’ monolayers have intrinsic long-range ferromagnetic orders. Particularly, the Curie temperature of 1T-VSeTe monolayer is up to 100 K, which is greatly higher than 2D 1T-VSe<jats:sub>2</jats:sub> and 1T-VTe<jats:sub>2</jats:sub>. Furthermore, the six Janus VXX’ monolayers have similar crater-like ferroelastic switching curves. Compared to black phosphorus, 2H-VSSe monolayer has the similar ferroelastic switching signal and 4 times lower energy barrier. In addition, the out-of-plane piezoelectricity induced by the structure asymmetry in the vertical direction gives the 2H-VXX’ monolayers the potential to be piezoelectric materials. It is found that a built-in electric field in the vertical direction due to the different electronegativity values of chalcogen atoms induces the changes of electronic structures, which leads to the appearance of three different types of band gaps in the three H-phase structures. Recently, the experimental growth of the Janus MoSSe monolayers and the electrochemical exfoliation of ferromagnetic monolayered VSe<jats:sub>2</jats:sub> make the Janus VXX’ monolayers possibly fabricated in experiments.</jats:p>

<jats:p>It is known that the p–n junction of an absorption region is a crucial part for power conversion efficiency of photovoltaic power converters. We fabricate four samples with different dopant concentrations in base layers. The dependences of power conversion efficiency and fill factor on input power are displayed by photocurrent–voltage measurement. Photoluminescence characteristics under open circuit and connected circuit conditions are also studied. It is found that the status of p–n junction matching is the critical factor in affecting the power conversion efficiency. In addition, series resistance of photovoltaic power converters impairs the efficiency especially at high input powers. Both the key factors need to be considered to obtain high efficiency, and this work provides promising guidance on designing photovoltaic power converters.</jats:p>

<jats:p>We develop a tightly focused pump-probe absorption technique to study diffusion dynamics of photoexcited carriers. It has many advantages including the simple setup and operations, higher detection sensitivity, an analytic descriptive model and fast data samplings. Diffusion dynamics are measured twice, separately using two different-sized probe spots, instead of many time-delayed diffusion profiles of a carrier pocket measured using spatially probe-spot scanning. An analytic model is derived to describe diffusion dynamics. Diffusion dynamics in GaAs are measured to demonstrate the feasibility of this technique. The diffusion coefficient is obtained and agrees well with the reported experimental and theoretical results.</jats:p>

<jats:p>Few-layered gallium selenide (GaSe) is obtained by using the mechanical exfoliation method, and its properties are characterized by photoluminescence and Raman spectroscopy. The pressure-dependent phonon scatterings of bulk, few-layered, oxidized few-layered GaSe are characterized up to 30 GPa by using a diamond anvil cell with inert argon used as the pressure transmission medium. All the GaSe samples processed a phase transition around 28 GPa. A new vibration mode at 250 cm<jats:sup>−1</jats:sup> is found in oxidized few-layered GaSe by Raman spectra, which is indexed as the Raman vibration mode of <jats:italic>α</jats:italic>-Se.</jats:p>

<jats:p>Biological bipolar metaplasticities were successfully mimicked in two-dimensional (2D) MoS<jats:sub>2</jats:sub> transistors via the implementation of two different MoS<jats:sub>2</jats:sub> surface decorations, poly (vinyl alcohol) (PVA) and chitosan bio-polymers. Interestingly, the depressing metaplasticity was successfully mimicked when the PVA bio-polymer was used as the surface decoration layer, whereas the metaplasticity of long-term potentiation was realized when the chitosan bio-polymer was taken as the surface decoration layer. Furthermore, the electronic band structures of the 2D MoS<jats:sub>2</jats:sub> devices with different surface decorations were further investigated using first-principles calculations for understanding the underlying mechanisms of such bipolar metaplasticities. These results will deepen our understanding of metaplasticity, and have great potential in neuromorphic computing applications.</jats:p>

<jats:p>Van der Waals heterostructures (vdWHs) realized by vertically stacking of different two-dimensional (2D) materials are a promising candidate for tunneling devices because of their atomically clean and lattice mismatch-free interfaces in which different layers are separated by the vdW gaps. The gaps can provide an ideal electric modulation environment on the vdWH band structures and, on the other hand, can also impede the electron tunneling behavior because of large tunneling widths. Here, through first-principles calculations, we find that the electrically modulated tunneling behavior is immune to the interlayer interaction, keeping a direct band-to-band tunneling manner even the vdWHs have been varied to the indirect semiconductor, which means that the tunneling probability can be promoted through the vdW gap shrinking. Using transition metal dichalcogenide heterostructures as examples and normal strains as the gap reducing strategy, a maximum shrinking of 33% is achieved without changing the direct tunneling manner, resulting in a tunneling probability promotion of more than 45 times. Furthermore, the enhanced interlayer interaction by the strains will boost the stability of the vdWHs at the lateral direction, preventing the interlayer displacement effectively. It is expected that our findings provide perspectives in improving the electric behaviors of the vdWH devices.</jats:p>

<jats:p>Molecular dynamics simulations are performed to investigate the polymorphism and flexibility of DNA in water, ethylene glycol (EG) and ethanol (EA) solutions. DNA in EG resembles the structure of DNA in <jats:italic>water</jats:italic> exhibiting B-DNA. In contrast, the DNA is an A-DNA state in the EA. We demonstrate that one important cause of these A↔B state changes is the competition between hydration and direct cation coupling to the phosphate groups on DNA backbones. To DNA structural polymorphism, it is caused by competition between hydration and cation coupling to the base pairs on grooves. Unlike flexible DNA in water and EA, DNA is immobilized around the canonical structure in EG solution, eliminating the potential biological effects of less common non-canonical DNA sub-states.</jats:p>

<jats:p>Some problems with the article by Oluwadare and Oyewumi [<jats:italic>Chin. Phys. Lett.</jats:italic> 34 (2017) 110301] are discussed. The previously proposed solution of the Schrödinger wave equation in the generalized inverse quadratic Yukawa potential is unsatisfactory for a number of reasons.</jats:p>