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<jats:p>The current-induced spin-orbit torque (SOT) plays a dominant role to manipulate the magnetization in a heavy metal/ferromagnetic metal bilayer. We separate the contributions of interfacial and bulk spin-orbit coupling (SOC) to the effective field of field-like SOT in a typical NiFe/Pt bilayer by planar Hall effect (PHE). The effective field from interfacial SOC is directly measured at the transverse PHE configuration. Then, at the longitudinal configuration, the effective field from bulk SOC is determined, which is much smaller than that from interfacial SOC. The giant interface SOT in NiFe/Pt bilayers suggests that further analysis of interfacial effects on the current-induced manipulation of magnetization is necessary.</jats:p>

<jats:p>High quality 0.02 mol%, 0.05 mol%, and 0.08 mol% Fe: <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> single crystals were grown by the floating zone method. The crystal structure, optical, electrical, and thermal properties were measured and discussed. Fe: <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> single crystals showed transmittance of higher than 80% in the near infrared region. With the increase of the Fe doping concentration, the optical bandgaps reduced and room temperature resistivity increased. The resistivity of 0.08 mol% Fe: <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> crystal reached to 3.63 × 10<jats:sup>11</jats:sup> Ω ⋅cm. The high resistivity Fe: <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> single crystals could be applied as the substrate for the high-power field effect transistors (FETs).</jats:p>

<jats:p>Sulfide nanocrystals and their composites have shown great potential in the thermoelectric (TE) field due to their extremely low thermal conductivity. Recently a solid and hollow metastable Au<jats:sub>2</jats:sub>S nanocrystalline has been successfully synthesized. Herein, we study the TE properties of this bulk Au<jats:sub>2</jats:sub>S by first-principles calculations and semiclassical Boltzmann transport theory, which provides the basis for its further experimental studies. Our results indicate that the highly twofold degeneracy of the bands appears at the <jats:italic>Γ</jats:italic> point in the Brillouin zone, resulting in a high Seebeck coefficient. Besides, Au<jats:sub>2</jats:sub>S exhibits an ultra-low lattice thermal conductivity (∼ 0.88 W⋅m<jats:sup>−1</jats:sup>⋅K<jats:sup>−1</jats:sup> at 700 K). At 700 K, the thermoelectric figure of merit of the optimal p-type doping is close to 1.76, which is higher than 0.8 of ZrSb at 700 K and 1.4 of PtTe at 750 K. Our work clearly demonstrates the advantages of Au<jats:sub>2</jats:sub>S as a TE material and would greatly inspire further experimental studies and verifications.</jats:p>

<jats:p>Quantum theory of surface plasmons is very important for studying the interactions between light and different metal nanostructures in nanoplasmonics. In this work, using the canonical quantization method, the SPPs on nanowires and their orbital and spin angular momentums are investigated. The results show that the SPPs on nanowire carry both orbital and spin momentums during propagation. Later, the result is applied to the plasmonic nanowire waveguide to show the agreement of the theory. The study is helpful for the nano wire based plasmonic interactions and the quantum information based optical circuit in the future.</jats:p>

<jats:p>We theoretically investigate the optical absorption coefficient (OAC) in asymmetrical Gaussian potential quantum dots subject to an applied electric field. Confined wave functions together with energies of electron energies in an effective mass approximation framework are obtained. The OAC is expressed according to the iterative method and the compact-density-matrix approach. Based on our results, OAC is sensitively dependent on external electric field together with the incident optical intensity. Additionally, peak shifts into greater energy as the quantum dot radius decrease. Moreover, the parameters of Gaussian potential have a significant influence on the OAC.</jats:p>

<jats:p>Two types of enhancement-mode (E-mode) AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) with different gate insulators are fabricated on Si substrates. The HfO<jats:sub>2</jats:sub> gate insulator and the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> gate insulator each with a thickness of 30 nm are grown by the plasma-enhanced atomic layer deposition (PEALD). The energy band diagrams of two types of dielectric MIS-HEMTs are compared. The breakdown voltage (<jats:italic>V</jats:italic> <jats:sub>BR</jats:sub>) of HfO<jats:sub>2</jats:sub> dielectric layer and Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> dielectric layer are 9.4 V and 15.9 V, respectively. With the same barrier thickness, the transconductance of MIS-HEMT with HfO<jats:sub>2</jats:sub> is larger. The threshold voltage (<jats:italic>V</jats:italic> <jats:sub>th</jats:sub>) of the HfO<jats:sub>2</jats:sub> and Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> MIS-HEMT are 2.0 V and 2.4 V, respectively, when the barrier layer thickness is 0 nm. The <jats:italic>C</jats:italic>–<jats:italic>V</jats:italic> characteristics are in good agreement with the <jats:italic>V</jats:italic> <jats:sub>th</jats:sub>’s transfer characteristics. As the barrier layer becomes thinner, the drain current density decreases sharply. Due to the dielectric/AlGaN interface is very close to the channel, the scattering of interface states will lead the electron mobility to decrease. The current collapse and the <jats:italic>R</jats:italic> <jats:sub>on</jats:sub> of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> MIS-HEMT are smaller at the maximum gate voltage. As Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> has excellent thermal stability and chemical stability, the interface state density of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/AlGaN is less than that of HfO<jats:sub>2</jats:sub>/AlGaN.</jats:p>

<jats:p>We study superconducting properties of NbN thin film samples with different thicknesses and an ultra-thin NbTiN meander nanowire sample. For the ultra-thin samples, we found that the temperature dependence of upper critical field (<jats:italic>H</jats:italic> <jats:sub>c2</jats:sub>) in parallel to surface orientation shows bending curvature close to critical temperature <jats:italic>T</jats:italic> <jats:sub>c</jats:sub>, suggesting a two-dimensional (2D) nature of the samples. The 2D behavior is further supported by the angular dependence measurements of <jats:italic>H</jats:italic> <jats:sub>c2</jats:sub> for the thinnest samples. The temperature dependence of parallel upper critical field for the thick films could be described by a model based on the anisotropic Ginzburg–Landau theory. Interestingly, the results measured in the field perpendicular to the film surface orientation show a similar bending curvature but in a much narrow temperature region close to <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> for the ultra-thin samples. We suggest that this feature could be due to suppression of pair-breaking caused by local in-homogeneity. We further propose the temperature dependence of perpendicular <jats:italic>H</jats:italic> <jats:sub>c2</jats:sub> as a measure of uniformity of superconducting ultra-thin films. For the thick samples, we find that <jats:italic>H</jats:italic> <jats:sub>c2</jats:sub> shows maxima for both parallel and perpendicular orientations. The <jats:italic>H</jats:italic> <jats:sub>c2</jats:sub> peak for the perpendicular orientation is believed to be due to the columnar structure formed during the growth of the thick films. The presence of columnar structure is confirmed by transmission electron microscopy (TEM). In addition, we have measured the angular dependence of magneto-resistance, and the results are consistent with the <jats:italic>H</jats:italic> <jats:sub>c2</jats:sub> data.</jats:p>

<jats:p>We report experimental investigation of the resistivity and Nernst effect in two-dimensional (2D) NbSe<jats:sub>2</jats:sub> crystals. A strongly enhanced Nernst effect, 100 times larger than that in bulk NbSe<jats:sub>2</jats:sub>, caused by moving vortices is observed in thin film. It is found that in the low temperature, high magnetic field regime, pinning effects show little dependence on the thickness and resistivity of the superconductor films. Strong Nernst signals persist above the superconducting transition, suggesting that the Nernst effect is a sensitive probe to superconducting fluctuations. A magnetic field induced superconductor--insulator transition (SIT) is evident, which is surprising in that such a SIT usually takes place in disordered dirty superconductors, while our samples are highly crystalline and close to the clean limit. Hence, our results expand the scope of SIT into 2D crystal clean superconductors.</jats:p>

<jats:p>The linear and nonlinear optical absorption coefficients (ACs) and refraction index changes (RICs) of 1s–1p, 1p–1d, and 1f–1d transitions are investigated in a wurtzite In<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Ga<jats:sub>1 – <jats:italic>x</jats:italic> </jats:sub>N/GaN core–shell quantum dot (CSQD) with donor impurity by using density matrix approach. The effects of built-in electric field (BEF), ternary mixed crystal (TMC), impurity, and CSQD size are studied in detail. The finite element method is used to calculate the ground and excited energy state energy and wave function. The results reveal that the BEF has a great influence on the linear, nonlinear, and total ACs and RICs. The presence of impurity leads the resonant peaks of the ACs and RICs to be blue-shifted for all transitions, especially for 1s–1p transition. It is also found that the resonant peaks of the ACs and RICs present a red shift with In-composition decreasing or core radius increasing. Moreover, the amplitudes of the ACs and RICs are strongly affected by the incident optical intensity. The absorption saturation is more sensitive without the impurity than with the impurity, and the appearance of absorption saturation requires a larger incident optical intensity when considering the BEF.</jats:p>

<jats:p>The dissolution of transition metal (TM) cations from oxide cathodes and the subsequent migration and deposition on the anode lead to the deconstruction of cathode materials and uncontrollable growth of solid electrode interphase (SEI). The above issues have been considered as main causes for the performance degradation of lithium-ion batteries (LIBs). In this work, we reported that the solid oxide electrolyte Li<jats:sub>1.5</jats:sub>Al<jats:sub>0.5</jats:sub>Ti<jats:sub>1.5</jats:sub>(PO<jats:sub>4</jats:sub>)<jats:sub>3</jats:sub> (LATP) coating on polyethylene (PE) polymer separator can largely block the TM dissolution and deposition in LIBs. Scanning electron microscopy (SEM), second ion mass spectroscopy (SIMS), and Raman spectroscopy characterizations reveal that the granular surface of the LATP coating layer is converted to a dense morphology due to the reduction of LATP at discharge process. The as-formed dense surface layer can effectively hinder the TM deposition on the anode electrode and inhibit the TM dissolution from the cathode electrode. As a result, both the LiCoO<jats:sub>2</jats:sub>/SiO-graphite and LiMn<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub>/SiO-graphite cells using LATP coated PE separator show substantially enhanced cycle performances compared with those cells with Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> coated PE separator.</jats:p>