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<jats:p>Topological materials have aroused great interest in recent years, especially when magnetism is involved. Pressure can effectively tune the topological states and possibly induce superconductivity. Here we report the high-pressure study of topological semimetals <jats:italic>X</jats:italic>Cd<jats:sub>2</jats:sub>Sb<jats:sub>2</jats:sub> (<jats:italic>X</jats:italic> = Eu and Yb), which have the same crystal structure. In antiferromagnetic (AFM) Weyl semimetal EuCd<jats:sub>2</jats:sub>Sb<jats:sub>2</jats:sub>, the Néel temperature (<jats:italic>T</jats:italic> <jats:sub>N</jats:sub>) increases from 7.4 K at ambient pressure to 50.9 K at 14.9 GPa. When pressure is above 14.9 GPa, the AFM peak of resistance disappears, indicating a non-magnetic state. In paramagnetic Dirac semimetal candidate YbCd<jats:sub>2</jats:sub>Sb<jats:sub>2</jats:sub>, pressure-induced superconductivity appears at 1.94 GPa, then <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> reaches to a maximum of 1.67 K at 5.22 GPa and drops to zero at about 30 GPa, displaying a dome-shaped temperature–pressure phase diagram. High-pressure x-ray diffraction measurement demonstrates that a crystalline-to-amorphous phase transition occurs at about 16 GPa in YbCd<jats:sub>2</jats:sub>Sb<jats:sub>2</jats:sub>, revealing the robustness of pressure-induced superconductivity against structural instability. Similar structural phase transition may also occur in EuCd<jats:sub>2</jats:sub>Sb<jats:sub>2</jats:sub>, causing the disappearance of magnetism. Our results show that <jats:italic>X</jats:italic>Cd<jats:sub>2</jats:sub>Sb<jats:sub>2</jats:sub> (<jats:italic>X</jats:italic> = Eu and Yb) is a novel platform for exploring the interplay among magnetism, topology, and superconductivity.</jats:p>

<jats:p>Nonisovalent (GaN)<jats:sub>1−<jats:italic>x</jats:italic> </jats:sub>(ZnO)<jats:sub> <jats:italic>x</jats:italic> </jats:sub> alloys are more technologically promising than their binary counterparts because of the abruptly reduced band gap. Unfortunately, the lack of two-dimensional (2D) configurations as well as complete stoichiometries hinders to further explore the thermal transport, thermoelectrics, and adsorption/permeation. We identify that multilayer (GaN)<jats:sub>1−<jats:italic>x</jats:italic> </jats:sub>(ZnO)<jats:sub> <jats:italic>x</jats:italic> </jats:sub> stabilize as wurtzite-like <jats:italic>Pm</jats:italic>-(GaN)<jats:sub>3</jats:sub>(ZnO)<jats:sub>1</jats:sub>, <jats:italic>Pmc</jats:italic>2<jats:sub>1</jats:sub>-(GaN)<jats:sub>1</jats:sub>(ZnO)<jats:sub>1</jats:sub>, <jats:italic>P</jats:italic>3<jats:italic>m</jats:italic>1-(GaN)<jats:sub>1</jats:sub>(ZnO)<jats:sub>2</jats:sub>, and haeckelite <jats:italic>C</jats:italic>2/<jats:italic>m</jats:italic>-(GaN)<jats:sub>1</jats:sub>(ZnO)<jats:sub>3</jats:sub> via structural searches. <jats:italic>P</jats:italic>3<jats:italic>m</jats:italic>1-(GaN)<jats:sub>1</jats:sub>(ZnO)<jats:sub>2</jats:sub> shares the excellent thermoelectrics with the figure of merit <jats:italic>ZT</jats:italic> as high as 3.08 at 900 K for the p-type doping due to the ultralow lattice thermal conductivity, which mainly arises from the strong anharmonicity by the interlayer asymmetrical charge distributions. The <jats:italic>p</jats:italic>–<jats:italic>d</jats:italic> coupling is prohibited from the group theory in <jats:italic>C</jats:italic>2/<jats:italic>m</jats:italic>-(GaN)<jats:sub>1</jats:sub>(ZnO)<jats:sub>3</jats:sub>, which thereby results in the anomalous band structure versus ZnO composition. To unveil the adsorption/permeation of H<jats:sup>+</jats:sup>, Na<jats:sup>+</jats:sup>, and OH<jats:sup>−</jats:sup> ions in <jats:italic>AA</jats:italic>-stacking configurations, the potential wells and barriers are explored from the Coulomb interaction and the ionic size. Our work is helpful in experimental fabrication of novel optoelectronic and thermoelectric devices by 2D (GaN)<jats:sub>1−<jats:italic>x</jats:italic> </jats:sub>(ZnO)<jats:sub> <jats:italic>x</jats:italic> </jats:sub> alloys.</jats:p>

<jats:p>Phase image in tapping-mode atomic force microscope (TM-AFM) results from various dissipations in a microcantilever system. The phases mainly reflect the tip-sample contact dissipations which allow the nanoscale characteristics to be distinguished from each other. In this work, two factors affecting the phase and phase contrast are analyzed. It is concluded from the theoretical and experimental results that the phases and phase contrasts in the TM-AFM are related to the excitation frequency and energy dissipation of the system. For a two-component blend, it is theoretically and experimentally proven that there exists an optimal excitation frequency for maximizing the phase contrast. Therefore, selecting the optimal excitation frequency can potentially improve the phase contrast results. In addition, only the key dissipation between the tip and sample is found to accurately reflect the sample properties. Meanwhile, the background dissipation can potentially reduce the contrasts of the phase images and even mask or distort the effective information in the phase images. In order to address the aforementioned issues, a self-excited method is adopted in this study in order to eliminate the effects of the background dissipation on the phases. Subsequently, the real phase information of the samples is successfully obtained. It is shown in this study that the eliminating of the background dissipation can effectively improve the phase contrast results and the real phase information of the samples is accurately reflected. These results are of great significance in optimizing the phases of two-component samples and multi-component samples in atomic force microscope.</jats:p>

<jats:p>Charge density wave (CDW) strongly affects the electronic properties of two-dimensional (2D) materials and can be tuned by phase engineering. Among 2D transitional metal dichalcogenides (TMDs), VTe<jats:sub>2</jats:sub> was predicted to require small energy for its phase transition and shows unexpected CDW states in its T-phase. However, the CDW state of H-VTe<jats:sub>2</jats:sub> has been barely reported. Here, we investigate the CDW states in monolayer (ML) H-VTe<jats:sub>2</jats:sub>, induced by phase-engineering from T-phase VTe<jats:sub>2</jats:sub>. The phase transition between T- and H-VTe<jats:sub>2</jats:sub> is revealed with x-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) measurements. For H-VTe<jats:sub>2</jats:sub>, scanning tunneling microscope (STM) and low-energy electron diffraction (LEED) results show a robust <jats:inline-formula> <jats:tex-math> <?CDATA $2\sqrt{3}\times 2\sqrt{3}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>2</mml:mn> <mml:msqrt> <mml:mn>3</mml:mn> </mml:msqrt> <mml:mo>×</mml:mo> <mml:mn>2</mml:mn> <mml:msqrt> <mml:mn>3</mml:mn> </mml:msqrt> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_31_7_077101_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> CDW superlattice with a transition temperature above 450 K. Our findings provide a promising way for manipulating the CDWs in 2D materials and show great potential in its application of nanoelectronics.</jats:p>

<jats:p>(1 – <jats:italic>x</jats:italic>)MnFe<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> (MFO)/<jats:italic>x</jats:italic>ZnMn<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> (ZMO) (<jats:italic>x</jats:italic> = 0, 0.2, 0.5, 0.8, and 1.0) nanocomposite samples were prepared using co-precipitation procedure. The phase percentage, cell parameters, and crystallite size of MFO and ZMO phases in each nanocomposite sample were calculated using Rietveld refinement procedure. The x-ray diffraction (XRD) analysis and Fourier-transform infrared spectroscopy techniques established the variation in the lattice parameters of each phase are due to permutation of all cations among the octahedral and tetrahedral sites of MFO and ZMO. The different oxidation states of different ions in all samples were determined using x-ray photoelectron spectroscopy (XPS) technique. The variation in absorbance of the nanocomposite samples with composition parameter (<jats:italic>x</jats:italic>) is dependent on the wavelength region. The optical bandgap of the nanocomposite samples is decreased as the content of ZMO phase increased. The effect of alloying on the refractive index, extinction coefficient, dielectric constant, optical conductivity, and the nonlinear optical behaviors of all samples were studied in detail. The nanocomposite sample <jats:italic>x</jats:italic> = 0.5 disclosed upgraded optical parameters with the highest refractive index, optical conductivity, and PL intensity, which nominate it to be functional in various application fields.</jats:p>

<jats:p>We study theoretically Josephson effect in a planar ballistic junction between two triplet superconductors with <jats:italic>p</jats:italic>-wave orbital symmetries and separated by a two-dimensional (2D) semiconductor channel with strong Rashba spin–orbit coupling. In triplet superconductors, three types of orbital symmetries are considered. We use Bogoliubov–de Gennes formalism to describe quasiparticle propagations through the junction and the supercurrents are calculated in terms of Andreev reflection coefficients. The features of the variation of the supercurrents with the change of the strength of Rashba spin–orbit coupling are investigated in some detail. It is found that for the three types of orbital symmetries considered, both the magnitudes of supercurrent and the current-phase relations can be manipulated effectively by tuning the strength of Rashba spin–orbit coupling. The interplay of Rashba spin–orbit coupling and Zeeman magnetic field on supercurrent is also investigated in some detail.</jats:p>

<jats:p>Using the first-principles method, the spin-dependent transport properties of a novel platform molecule containing a freestanding molecular wire is investigated by simulating the spin-polarized scanning tunneling microscope experiment with Ni tip and Au substrate electrodes. Transport calculations show that the total current increases as the tip gradually approaches to the substrate, which is consistent with the conductance obtained from previous experiment. More interestingly, the spin polarization (SP) of current modulated by compression effect has the completely opposite trend to the total current. Transmission analyses reveal that the reduction of SP of current with compression process originates from the promotion of spin-down electron channel, which is controlled by deforming the molecule wire. In addition, the density of states shows that the SP of current is directly affected by the organic–ferromagnetic spinterface. The weak orbital hybridization between the Ni tip and propynyl of molecule results in high interfacial SP, whereas the breaking of the C≡C triple of propynyl in favor of the Ni–C–C bond induces the strong orbital hybridization and restrains the interfacial SP. This work proposes a new way to control and design the SP of current through organic–ferromagnetic spinterface using functional molecular platform.</jats:p>

<jats:p>The understanding of the influence of electrode characteristics on charge transport is essential in the field of molecular electronics. In this work, we investigate the electronic transport properties of molecular junctions comprising methylthiol-terminated permethyloligosilanes and face-centered crystal Au/Ag electrodes with crystallographic orientations of (111) and (100), based on the <jats:italic>ab initio</jats:italic> quantum transport simulations. The calculations reveal that the molecular junction conductance is dominated by the electronic coupling between two interfacial metal–S bonding states, which can be tuned by varying the molecular length, metal material of the electrodes, and crystallographic orientation. As the permethyloligosilane backbone elongates, although the <jats:italic>σ</jats:italic> conjugation increases, the decreasing of coupling induced by the increasing number of central Si atoms reduces the junction conductance. The molecular junction conductance of methylthiol-terminated permethyloligosilanes with Au electrodes is higher than that with Ag electrodes with a crystallographic orientation of (111). However, the conductance trend is reversed when the electrode crystallographic orientation varies from (111) to (100), which can be ascribed to the reversal of interfacial coupling between two metal–S interfacial states. These findings are conducive to elucidating the mechanism of molecular junctions and improving the transport properties of molecular devices by adjusting the electrode characteristics.</jats:p>

<jats:p>A two-dimensional (2D) surface-enhanced Raman scattering (SERS) substrate is fabricated by decorating carbon nanotube (CNT) films with Ag nanoparticles (AgNPs) in different sizes, via simple and low-cost chemical reduction method and self-assembling method. The change of Raman and SERS activity of carbon nanotubes/Ag nanoparticles (CNTs/AgNPs) composites with varying size of AgNPs are investigated by using rhodamine 6G (R6G) as a probe molecule. Meanwhile, the scattering cross section of AgNPs and the distribution of electric field of CNTs/AgNPs composite are simulated through finite difference time domain (FDTD) method. Surface plasmon resonance (SPR) wavelength is redshifted as the size of AgNPs increases, and the intensity of SERS and electric field increase with AgNPs size increasing. The experiment and simulation results show a Raman scattering enhancement factor (EF) of 10<jats:sup>8</jats:sup> for the hybrid substrate.</jats:p>

<jats:p>Voltage control magnetism has been widely studied due to its potential applications in the next generation of information technology. PMN-PT, as a single crystal ferroelectric substrate, has been widely used in the study of voltage control magnetism because of its excellent piezoelectric properties. However, most of the research based on PMN-PT only studies the influence of a single tensile (or compressive) stress on the magnetic properties due to the asymmetry of strain. In this work, we show the effect of different strains on the magnetic anisotropy of an Fe<jats:sub>19</jats:sub>Ni<jats:sub>81</jats:sub>/(011) PMN-PT heterojunction. More importantly, the (011) cut PMN-PT generates non-volatile strain, which provides an advantage when investigating the voltage manipulation of RF/microwave magnetic devices. As a result, a ferromagnetic resonance field tunability of 70 Oe is induced in our sample by the non-volatile strain. Our results provide new possibilities for novel voltage adjustable RF/microwave magnetic devices and spintronic devices.</jats:p>