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<jats:p>A near-infrared germanium (Ge) Schottky photodetector (PD) with an ultrathin silicon (Si) barrier enhancement layer between the indium-doped tin oxide (ITO) electrode and Ge epilayer on Si or silicon-on-insulator (SOI) is proposed and fabricated. The well-behaved ITO/Si cap/Ge Schottky junctions without intentional doping process for the Ge epilayer are formed on the Si and SOI substrates. The Si- and SOI-based ITO/Si cap/Ge Schottky PDs exhibit low dark current densities of 33 mA/cm<jats:sup>2</jats:sup> and 44 mA/cm<jats:sup>2</jats:sup>, respectively. Benefited from the high transmissivity of ITO electrode and the reflectivity of SOI substrate, an optical responsivity of 0.19 A/W at 1550 nm wavelength is obtained for the SOI-based ITO/Si cap/Ge Schottky PD. These complementary metal–oxide–semiconductor (CMOS) compatible Si (or SOI)-based ITO/Si cap/Ge Schottky PDs are quite useful for detecting near-infrared wavelengths with high efficiency.</jats:p>

<jats:p>Using the first principles calculation and Boltzmann transport theory, we study the thermoelectric properties of Si<jats:sub>2</jats:sub>BN adsorbing halogen atoms (Si<jats:sub>2</jats:sub>BN-4<jats:italic>X</jats:italic>, <jats:italic>X</jats:italic> = F, Cl, Br, and I). The results show that the adsorption of halogen atoms can significantly regulate the energy band structure and lattice thermal conductivity of Si<jats:sub>2</jats:sub>BN. Among them, Si<jats:sub>2</jats:sub>BN-4I has the best thermoelectric performance, the figure of merit can reach 0.50 K at 300 K, which is about 16 times greater than that of Si<jats:sub>2</jats:sub>BN. This is because the adsorption of iodine atoms not only significantly increases the Seebeck coefficient due to band degeneracy, but also rapidly reduces the phonon thermal conductivity by enhancing phonon scattering. Our work proves the application potential of Si<jats:sub>2</jats:sub>BN-based crystals in the field of thermoelectricity and the effective method for metal crystals to open bandgaps by adsorbing halogens.</jats:p>

<jats:p>The double perovskite Ca<jats:sub>2</jats:sub>CrSbO<jats:sub>6</jats:sub> exhibits a ferromagnetic long-range order below <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> = 13 K and a saturation magnetization of 2.35 <jats:italic>μ</jats:italic> <jats:sub>B</jats:sub> at 2 K. In this study, the polycrystalline Ca<jats:sub>2</jats:sub>CrSbO<jats:sub>6</jats:sub> is synthesized under high pressure and high temperature, and the critical behavior of the ferromagnetic material as well as the effects of the magnetic behavior due to the isovalent substitution of Sr<jats:sup>2+</jats:sup> for Ca<jats:sup>2+</jats:sup> is investigated. Also studied are the ferromagnetic criticality of the double perovskite Ca<jats:sub>2</jats:sub>CrSbO<jats:sub>6</jats:sub> at the ferromagnetic transition temperature <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> ≈ 12.6 K from the isotherms of magnetization <jats:italic>M</jats:italic>(<jats:italic>H</jats:italic>) <jats:italic>via</jats:italic> an iteration process and the Kouvel–Fisher method. The critical exponents associated with the transition are determined as follows: <jats:italic>β</jats:italic> = 0.322, <jats:italic>γ</jats:italic> = 1.241, and <jats:italic>δ</jats:italic> = 4.84. The magnetization data in the vicinity of <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> can be scaled into two universal curves in the plot of <jats:italic>M</jats:italic>/| <jats:italic>ε</jats:italic> |<jats:sup> <jats:italic>β</jats:italic> </jats:sup> <jats:italic>versus</jats:italic> <jats:italic>H</jats:italic>/| <jats:italic>ε</jats:italic> |<jats:sup> <jats:italic>β</jats:italic> + <jats:italic>γ</jats:italic> </jats:sup>, where <jats:italic>ε</jats:italic> = <jats:italic>T</jats:italic>/<jats:italic>T</jats:italic> <jats:sub>c</jats:sub> – 1. The obtained <jats:italic>β</jats:italic> and <jats:italic>γ</jats:italic> values are consistent with the predicted values from a three-dimensional Ising model. The effects of Sr substitution on the double perovskite Ca<jats:sub>2</jats:sub>CrSbO<jats:sub>6</jats:sub> are taken into consideration. As the Sr content increases, the (Ca<jats:sub>2 – <jats:italic>x</jats:italic> </jats:sub>Sr<jats:sub> <jats:italic>x</jats:italic> </jats:sub>)CrSbO<jats:sub>6</jats:sub> polycrystal shows a continuous switch from ferromagnetic to antiferromagnetic behavior.</jats:p>

<jats:p>We investigate the angular-dependent multi-mode resonance frequencies in CoZr magnetic thin films with a rotatable stripe domain structure. A variable range of multi-mode resonance frequencies from 1.86 GHz to 4.80 GHz is achieved by pre-magnetizing the CoZr films along different azimuth directions, which can be ascribed to the competition between the uniaxial anisotropy caused by the oblique deposition and the rotatable anisotropy induced by the rotatable stripe domain. Furthermore, the regulating range of resonance frequency for the CoZr film can be adjusted by changing the oblique deposition angle. Our results might be beneficial for the applications of magnetic thin films in microwave devices.</jats:p>

<jats:p>The binary alloy/ferromagnetic metal heterostructure has drawn extensive attention in the research field of spin–orbit torque (SOT) due to the potential enhancement of SOT efficiency via composition engineering. In this work, the magnetic properties and SOT efficiency in the Pt<jats:sub>100 – <jats:italic>x</jats:italic> </jats:sub>Ni<jats:sub> <jats:italic>x</jats:italic> </jats:sub>/Ni<jats:sub>78</jats:sub>Fe<jats:sub>22</jats:sub> bilayers were investigated via the spin-torque ferromagnetic resonance (ST-FMR) technique. The effective magnetic anisotropy field and effective damping constant extracted by analyzing the ST-FMR spectra show a weak dependence on the Ni concentration. The effective spin-mixing conductance of 8.40 × 10<jats:sup>14</jats:sup> Ω<jats:sup>−1</jats:sup> ⋅ m<jats:sup>−2</jats:sup> and the interfacial spin transparency <jats:italic>T</jats:italic> <jats:sub>in</jats:sub> of 0.59 were obtained for the sample of Pt<jats:sub>70</jats:sub>Ni<jats:sub>30</jats:sub>/NiFe bilayer. More interestingly, the SOT efficiency that is carefully extracted from the angular dependence of ST-FMR spectra shows a nonmonotonic dependence on the Ni concentration, which reaches the maximum at <jats:italic>x</jats:italic> = 18. The enhancement of the SOT efficiency by alloying the Ni with Pt shows potential in lowering the critical switching current. Moreover, alloying relatively cheaper Ni with Pt may promote to reduce the cost of SOT devices.</jats:p>

<jats:p>A unified theoretical method is established to determine the charge-compensated <jats:italic>C</jats:italic> <jats:sub>3<jats:italic>v</jats:italic> </jats:sub> (II) centers of Er<jats:sup>3+</jats:sup> ions in CdF<jats:sub>2</jats:sub> and CaF<jats:sub>2</jats:sub> crystals by simulating the electron paramagnetic resonance (EPR) parameters and Stark energy levels. The potential (Er<jats:sup>3+</jats:sup>–F<jats:sup>−</jats:sup>–<jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{O}}}_{4}^{2-}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi mathvariant="normal">O</mml:mi> <mml:mn>4</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_30_3_037601_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) and (Er<jats:sup>3+</jats:sup>–<jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{F}}}_{7}^{-}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi mathvariant="normal">F</mml:mi> <mml:mn>7</mml:mn> <mml:mo>−</mml:mo> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_30_3_037601_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>–O<jats:sup>2–</jats:sup>) structures for the <jats:italic>C</jats:italic> <jats:sub>3<jats:italic>v</jats:italic> </jats:sub> (II) centers of Er<jats:sup>3+</jats:sup> ions in CdF<jats:sub>2</jats:sub> and CaF<jats:sub>2</jats:sub> crystals are checked by diagonalizing 364 × 364 complete energy matrices in the scheme of superposition model. Our studies indicate that the <jats:italic>C</jats:italic> <jats:sub>3<jats:italic>v</jats:italic> </jats:sub> (II) centers of Er<jats:sup>3+</jats:sup> ions in CdF<jats:sub>2</jats:sub> and CaF<jats:sub>2</jats:sub> may be ascribed to the local (Er<jats:sup>3+</jats:sup>–F<jats:sup>−</jats:sup>–<jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{O}}}_{4}^{2-}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi mathvariant="normal">O</mml:mi> <mml:mn>4</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_30_3_037601_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>) structure, where the upper ligand ion F<jats:sup>−</jats:sup> undergoes an off-center displacement by Δ<jats:italic>Z</jats:italic> ≈ 0.3 Å for CdF<jats:sub>2</jats:sub> and Δ<jats:italic>Z</jats:italic> ≈ 0.29 Å for the CaF<jats:sub>2</jats:sub> along the <jats:italic>C</jats:italic> <jats:sub>3</jats:sub> axis. Meanwhile, a local compressed distortion of the <jats:inline-formula> <jats:tex-math><?CDATA ${({{\rm{ErFO}}}_{4})}^{6-}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mrow> <mml:mo>(</mml:mo> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">ErFO</mml:mi> </mml:mrow> <mml:mn>4</mml:mn> </mml:msub> </mml:mrow> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> <mml:mrow> <mml:mn>6</mml:mn> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_30_3_037601_ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> cluster is expected to be Δ<jats:italic>R</jats:italic> ≈ 0.07 Å for CdF<jats:sub>2</jats:sub>:Er<jats:sup>3+</jats:sup> and Δ<jats:italic>R</jats:italic> ≈ 0.079 Å for CaF<jats:sub>2</jats:sub>:Er<jats:sup>3+</jats:sup>. The considerable <jats:italic>g</jats:italic>-factor anisotropy for Er<jats:sup>3+</jats:sup> ions in each of both crystals is explained reasonably by the obtained local parameters. Furthermore, our studies show that a stronger covalent effect exists in the <jats:italic>C</jats:italic> <jats:sub>3<jats:italic>v</jats:italic> </jats:sub> (II) center for Er<jats:sup>3+</jats:sup> in CaF<jats:sub>2</jats:sub> or CaF<jats:sub>2</jats:sub>, which may be due to the stronger electrostatic interaction and closer distance between the central Er<jats:sup>3+</jats:sup> ion and ligand O<jats:sup>2–</jats:sup> with the (Er<jats:sup>3+</jats:sup>–F<jats:sup>−</jats:sup>–<jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{O}}}_{4}^{2-}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi mathvariant="normal">O</mml:mi> <mml:mn>4</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_30_3_037601_ieqn5.gif" xlink:type="simple" /> </jats:inline-formula>) structure.</jats:p>

<jats:p>Most of the current graphene plasmonic researches are based on the substrates with isotropic dielectric constant such as silicon. In this work, we investigate optical properties of graphene nanoribbon arrays placed on a uniaxially anisotropic substrate, where the anisotropy provides an additional freedom to tune the behaviors of graphene plasmons, and its effect can be described by a simple effective formula. In practice, the substrates of semi-infinite and finite thickness are discussed by using both the formula and full wave simulations. Particularly, the dielectric constants <jats:italic>ε</jats:italic> <jats:sub>∥</jats:sub> and <jats:italic>ε</jats:italic> <jats:sub>⊥</jats:sub> approaching zero are intensively studied, which show different impacts on the transverse magnetic (TM) surface modes. In reality, the hexagonal boron nitride (hBN) can be chosen as the anisotropic substrate, which is also a hyperbolic material in nature.</jats:p>

<jats:p>Both Nb and Mo additions play a vital role in FeCo-based alloys and it is crucial to understand their roles and contents on thermal behavior, microstructural feature and magnetic property of alloys. Nanocrystalline alloy ribbons Fe<jats:sub>40</jats:sub>Co<jats:sub>40</jats:sub>Zr<jats:sub>9 – <jats:italic>y</jats:italic> </jats:sub>M<jats:sub> <jats:italic>y</jats:italic> </jats:sub>B<jats:sub>10</jats:sub>Ge<jats:sub>1</jats:sub> (<jats:italic>y</jats:italic> = 0–4; M = Nb, Mo) were prepared by crystallizing the as-quenched amorphous alloys. The effects of Nb and Mo additions on structures and properties of the Fe<jats:sub>40</jats:sub>Co<jats:sub>40</jats:sub>Zr<jats:sub>9</jats:sub>B<jats:sub>10</jats:sub>Ge<jats:sub>1</jats:sub> alloy are investigated systemically and compared. With increasing Nb or Mo content, the primary crystallization temperature, grain size of <jats:italic>α</jats:italic>-Fe(Co) phase and coercivity <jats:italic>H</jats:italic> <jats:sub>c</jats:sub> all decrease. Moreover, the effect of Mo addition on thermal behavior, microstructure and magnetic properties of the FeCoZrBGe alloy is greater compared to Nb addition. The gap between primary and secondary crystallization peaks of Mo-containing alloys is wider than that of Nb-containing alloys. Both grain size and <jats:italic>H</jats:italic> <jats:sub>c</jats:sub> of Mo-containing alloys are smaller than those of Nb-containing alloys. For Fe<jats:sub>40</jats:sub>Co<jats:sub>40</jats:sub>Zr<jats:sub>9</jats:sub>B<jats:sub>10</jats:sub>Ge<jats:sub>1</jats:sub> alloy, high Mo addition proportion is better compared to high Nb addition proportion.</jats:p>

<jats:p>By doping titanium hydride (TiH<jats:sub>2</jats:sub>) into boron carbide (B<jats:sub>4</jats:sub>C), a series of B<jats:sub>4</jats:sub>C + <jats:italic>x</jats:italic> wt% TiH<jats:sub>2</jats:sub> (<jats:italic>x</jats:italic> = 0, 5, 10, 15, and 20) composite ceramics were obtained through spark plasma sintering (SPS). The effects of the sintering temperature and the amount of TiH<jats:sub>2</jats:sub> additive on the microstructure, mechanical and electrical properties of the sintered B<jats:sub>4</jats:sub>C-TiB<jats:sub>2</jats:sub> composite ceramics were investigated. Powder mixtures of B<jats:sub>4</jats:sub>C with 0–20 wt% TiH<jats:sub>2</jats:sub> were heated from 1400 °C to 1800 °C for 20 min under 50 MPa. The results indicated that higher sintering temperatures contributed to greater ceramic density. With increasing TiH<jats:sub>2</jats:sub> content, titanium diboride (TiB<jats:sub>2</jats:sub>) formed between the TiH<jats:sub>2</jats:sub> and B<jats:sub>4</jats:sub>C matrix. This effectively improved Young’s modulus and fracture toughness of the composite ceramics, significantly improving their electrical properties: the electrical conductivity reached 114.9 S⋅cm<jats:sup>−1</jats:sup> at 1800 °C when <jats:italic>x</jats:italic> = 20. Optimum mechanical properties were obtained for the B<jats:sub>4</jats:sub>C ceramics sintered with 20 wt% TiH<jats:sub>2</jats:sub>, which had a relative density of 99.9 ± 0.1%, Vickers hardness of 31.8 GPa, and fracture toughness of 8.5 MPa⋅m<jats:sup>1 / 2</jats:sup>. The results indicated that the doping of fine Ti particles into the B<jats:sub>4</jats:sub>C matrix increased the conductivity and the fracture toughness of B<jats:sub>4</jats:sub>C.</jats:p>

<jats:p>To increase corrosion resistance of the sample, its electrical impedance must be increased. Due to the fact that electrical impedance depends on elements such as electrical resistance, capacitance, and inductance, by increasing the electrical resistance, reducing the capacitance and inductance, electrical impedance and corrosion resistance can be increased. Based on the fact that these elements depend on the type of material and the geometry of the material, multilayer structures with different geometries are proposed. For this purpose, conventional multilayer thin films, multilayer thin film including zigzag structure (zigzag 1) and multilayer thin film including double zigzag structure (zigzag 2) of manganese nitride are considered to protect AISI 304 stainless steel against corrosion in salt solution. These multilayer coatings including zigzag structures are prepared by alternately using the conventional deposition of thin film and glancing angle deposition method. After deposition, the samples are placed in a furnace under nitrogen flux for nitriding. The cross sections of the structures are observed by field emission scanning electron microscopy (FESEM). Atomic force microscope (AFM) is used to make surface analyses of the samples. The results show that the multilayer thin films including zigzag structures have smaller grains than conventional multilayer thin films, and the zigzag 2 structure has the smaller grain than the other two samples, which is attributed to the effect of shadowing and porosity on the oblique angle deposition method. Crystallography structures of the samples are studied by using x-ray diffraction (XRD) pattern and the results show that nitride phase formation in zigzag 2 structure is better than that in zigzag 1 structure and conventional multilayer thin film. To investigate the corrosion resistances of the structures, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests are performed. The results reveal that the multilayer thin films with zigzag structures have better corrosion protection than the conventional multilayer thin films, and the zigzag structure 2 has the smallest corrosion current and the highest corrosion resistance. The electrical impedances of the samples are investigated by simulating equivalent circuits. The high corrosion resistance of zigzag 2 structure as compared with conventional multilayer structure and zigzag 1 structure, is attributed to the high electrical impedance of the structure due to its small capacitance and high electrical resistance. Finally, the surfaces of corroded samples are observed by scanning electron microscope (SEM).</jats:p>