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<jats:p> <jats:italic>We report on magnetoresistance, Hall effect, and quantum Shubnikov–de Haas oscillation (SdH) experiments in NbIrTe<jats:sub>4</jats:sub> single crystals, which was recently predicted to be a type-II Weyl semimetal. NbIrTe<jats:sub>4</jats:sub> manifests a non-saturating and parabolic magnetoresistance at low temperatures. The magneto-transport measurements show that NbIrTe<jats:sub>4</jats:sub> is a multiband system. The analysis of the SdH oscillations reveals four distinct oscillation frequencies. Combined with the density-functional theory calculations, we show that they come from two types of Fermi surfaces: electron pocket E<jats:sub>1</jats:sub> and hole pocket H<jats:sub>2</jats:sub>.</jats:italic> </jats:p>

<jats:p> <jats:italic>We report single crystal growth of CoSi, which has recently been recognized as a new type of topological semimetal hosting fourfold and sixfold degenerate nodes. The Shubnikov–de Haas quantum oscillation (QO) is observed on our crystals. There are two frequencies originating from almost isotropic bulk electron Fermi surfaces, in accordance with band structure calculations. The effective mass, scattering rate, and QO phase difference of the two frequencies are extracted and discussed.</jats:italic> </jats:p>

<jats:p> <jats:italic>The spin-polarized photocurrent is used to study the in-plane electric field dependent spin transport in undoped InGaAs/AlGaAs multiple quantum wells. In the temperature range of 77–297 K, the spin-polarized photocurrent shows an anisotropic spin transport under different oriented in-plane electric fields. We ascribe this characteristic to two dominant mechanisms: the hot phonon effect and the Rashba spin-orbit effect which is influenced by the in-plane electric fields with different orientations. The formulas are proposed to fit our experiments, suggesting a guide of potential applications and devices</jats:italic>.</jats:p>

<jats:p> <jats:italic>Electrical transport properties of bismuth vanadate (BiVO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>) are studied under high pressures with electrochemical impedance spectroscopy. A pressure-induced ionic-electronic transition is found in BiVO</jats:italic> <jats:sub>4</jats:sub>. <jats:italic>Below 3.0 GPa, BiVO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>has ionic conduction behavior. The ionic resistance decreases under high pressures due to the increasing migration rate of O</jats:italic> <jats:sup>2−</jats:sup> <jats:italic>ions. Above 3.0 GPa the channels for ion migration are closed. Transport mechanism changes from the ionic to the electronic behavior. First-principles calculations show that bandgap width narrows under high pressures, causing the continuous decrease of electrical resistance of BiVO</jats:italic> <jats:sub>4</jats:sub>.</jats:p>

<jats:p> <jats:italic>FeTe, a non-superconducting parent compound in the iron-chalcogenide family, becomes superconducting after annealing in oxygen. Under the presence of magnetism, spin-orbit coupling, inhomogeneity and lattice distortion, the nature of its superconductivity is not well understood. Here we combine the mutual inductance technique with magneto transport to study the magnetization and superconductivity of FeTe thin films. It is found that the films with the highest T</jats:italic> <jats:sub>C</jats:sub> <jats:italic>show non-saturating superfluid density and a strong magnetic hysteresis distinct from that in a homogeneous superconductor. Such a hysteresis can be well explained by a two-level critical state model and suggests the importance of granularity to superconductivity in this compound</jats:italic>.</jats:p>

<jats:p> <jats:italic>The recently synthesized first</jats:italic> 4<jats:italic>d</jats:italic> <jats:italic>transition-metal oxide-hydride LaSr</jats:italic> <jats:sub>3</jats:sub> <jats:italic>NiRuO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>H</jats:italic> <jats:sub>4</jats:sub> <jats:italic>with the unusual high H:O ratio surprisingly displays no magnetic order down to 1.8 K. This is in sharp contrast to the similar unusual low-valent Ni</jats:italic> <jats:sup>+</jats:sup> <jats:italic>-Ru</jats:italic> <jats:sup>2+</jats:sup> <jats:italic>layered oxide LaSrNiRuO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>which has a rather high ferromagnetic (FM) ordering Curie temperature <jats:italic>T</jats:italic> <jats:sub>C</jats:sub> ∼ 250 K. Using density functional calculations with the aid of crystal field level diagrams and superexchange pictures, we find that the contrasting magnetism is due to the distinct spin-orbital states of the Ru</jats:italic> <jats:sup>2+</jats:sup> <jats:italic>ions (in addition to the common Ni</jats:italic> <jats:sup>+</jats:sup> <jats:italic>S</jats:italic> = 1/2 <jats:italic>state but with a different orbital state): the Ru</jats:italic> <jats:sup>2+</jats:sup> <jats:italic>S</jats:italic> = 0 <jats:italic>state in LaSr</jats:italic> <jats:sub>3</jats:sub> <jats:italic>NiRuO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>H</jats:italic> <jats:sub>4</jats:sub> <jats:italic>, but the Ru</jats:italic> <jats:sup>2+</jats:sup> <jats:italic>S</jats:italic> = 1 <jats:italic>state in LaSrNiRuO</jats:italic> <jats:sub>4</jats:sub>. <jats:italic>The Ru</jats:italic> <jats:sup>2+</jats:sup> <jats:italic>S</jats:italic> = 0 <jats:italic>state has the</jats:italic> (<jats:italic>xy</jats:italic>)<jats:sup>2</jats:sup>(<jats:italic>xz</jats:italic>,<jats:italic>yz</jats:italic>)<jats:sup>4</jats:sup> <jats:italic>occupation due to the RuH</jats:italic> <jats:sub>4</jats:sub> <jats:italic>O</jats:italic> <jats:sub>2</jats:sub> <jats:italic>octahedral coordination, and then the nonmagnetic Ru</jats:italic> <jats:sup>2+</jats:sup> <jats:italic>ions dilute the S</jats:italic> = 1/2 <jats:italic>Ni</jats:italic> <jats:sup>+</jats:sup> <jats:italic>sublattice which consequently has a very weak antiferromagnetic superexchange and thus accounts for the presence of no magnetic order down to 1.8 K in LaSr</jats:italic> <jats:sub>3</jats:sub> <jats:italic>NiRuO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>H</jats:italic> <jats:sub>4</jats:sub>. <jats:italic>In strong contrast, the Ru</jats:italic> <jats:sup>2+</jats:sup> <jats:italic>S</jats:italic> = 1 <jats:italic>state in LaSrNiRuO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>has the</jats:italic> (3<jats:italic>z</jats:italic> <jats:sup>2</jats:sup>–<jats:italic>r</jats:italic> <jats:sup>2</jats:sup>)<jats:sup>2</jats:sup>(<jats:italic>xz</jats:italic>,<jats:italic>yz</jats:italic>)<jats:sup>3</jats:sup>(<jats:italic>xy</jats:italic>)<jats:sup>1</jats:sup> <jats:italic>occupation due to the planar square RuO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>coordination, and then the multi-orbital FM superexchange between the S</jats:italic> = 1/2 <jats:italic>Ni</jats:italic> <jats:sup>+</jats:sup> <jats:italic>and S</jats:italic> = 1 <jats:italic>Ru</jats:italic> <jats:sup>2+</jats:sup> <jats:italic>ions gives rise to the high T</jats:italic> <jats:sub>C</jats:sub> <jats:italic>in LaSrNiRuO</jats:italic> <jats:sub>4</jats:sub>. <jats:italic>This work highlights the importance of spin-orbital states in determining the distinct magnetism</jats:italic>.</jats:p>

<jats:p> <jats:italic>An amorphous magnetic material system (Co</jats:italic> <jats:sub>20</jats:sub> <jats:italic>Fe</jats:italic> <jats:sub>47</jats:sub> <jats:italic>Ta</jats:italic> <jats:sub>20</jats:sub> <jats:italic>B</jats:italic> <jats:sub>13</jats:sub>)<jats:sub>1–<jats:italic>x</jats:italic> </jats:sub> <jats:italic>O</jats:italic> <jats:sub> <jats:italic>x</jats:italic> </jats:sub> <jats:italic>is fabricated by magneto sputtering. Three stages of magnetization behavior exist when oxygen content changes in the system. As the oxygen increases, the absence of percolation effect of magnetic nano-particles makes the multi-domain structure broken so that high coercivity appears in the samples with proper oxygen content. A temperature-dependent Stoner–Wohlfarth model is used to explain the magnetization properties at relatively high temperature. Magnetizations with magnetic field in and out of the sample plane are also investigated to prove the mechanisms. This work provides a systematic study of a new kind ofv amorphous magnetic system and is helpful for us to know more about this type of material</jats:italic>.</jats:p>

<jats:p> <jats:italic>MICAtronics, based on the functional oxide/mica heterostructures, has recently attracted much attention due to its potential applications in transparent, flexible electronics and devices. However, the weak van der Waals interaction decreases the tolerable lattice mismatch and thus limits the species of function oxides that are able to be epitaxially grown on mica. We successfully fabricate relatively high-quality epitaxial anatase TiO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>thin films on mica substrates. Structural analyses reveal that the carefully chosen growth temperature (650°C) and suitable crystalline phase (anatase phase) of TiO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>are the key issues for this van der Waals epitaxy. Moreover, as a buffer layer, the TiO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>layer successfully suppresses the decomposition of BiFeO</jats:italic> <jats:sub>3</jats:sub> <jats:italic>and the difficulty of epitaxial growth of BiFeO</jats:italic> <jats:sub>3</jats:sub> <jats:italic>is decreased. Therefore, relatively high-quality anatase TiO<jats:sub>2</jats:sub> is proved to be an effective buffer layer for fabricating more functional oxides on mica</jats:italic>.</jats:p>

<jats:p> <jats:italic>The mechanism for the self-assembly of hollow micelles from rod-coil diblock copolymers is proposed. In a coil-selective solvent, the diblock copolymers self-assemble into a layered structure. It is assumed that the rigid rods form an elastic shell whose properties are dictated by a bending energy. For a hollow micelle, the coils outside the micelle form a brush, while the coils inside the micelle can be in two different states, a brush or an adsorption layer, corresponding to symmetric or asymmetric configurations, respectively. The total energy density of a hollow micelle is calculated by combining the interfacial energy, elastic bending energy and the stretching energy of the brushes. For the asymmetric configuration with a polymer brush on one side, the competition between the elastic bending energy and the brush stretching energy leads to a finite spontaneous curvature, stabilizing hollow spherical micelles. Comparison of the free energy density for different geometries demonstrates that transitions for the different geometry micelles are controlled by the degree of polymerization of the coils and the length of the rods. These results are in agreement with the experimental results</jats:italic>.</jats:p>

<jats:p> <jats:italic>Plasma treatment is a powerful tool to tune the properties of two-dimensional materials. Previous studies have utilized various plasma treatments on two-dimensional materials. We find a new effect of plasma treatment. After controlled oxygen-plasma treatment on field-effect transistors based on two-dimensional SnSe</jats:italic> <jats:sub>2</jats:sub> <jats:italic>, the capacitive coupling between the silicon back gate and the channel through the 300nm SiO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>dielectric can be dramatically enhanced by about two orders of magnitude (from 11 nF/cm</jats:italic> <jats:sup>2</jats:sup> <jats:italic>to 880 nF/cm</jats:italic> <jats:sup>2</jats:sup> <jats:italic>), reaching good efficiency of ion-liquid gating. At the same time, plasma treated devices show large hysteresis in the gate sweep demonstrating memory behavior. We reveal that this spontaneous ion gating and hysteresis are achieved with the assistance of a thin layer of water film automatically formed on the sample surface with water molecules from the ambient air, due to the change in hydrophilicity of the plasma treated samples. The water film acts as the ion liquid to couple the back gate and the channel. Thanks to the rich carrier dynamics in plasma-treated two-dimensional transistors, synaptic functions are realized to demonstrate short- and long-term memories in a single device. This work provides a new perspective on the effects of plasma treatment and a facile route for realizing neuromorphic devices</jats:italic>.</jats:p>