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<jats:p>All-inorganic perovskite quantum dots (QDs) have drawn much attention due to their prominent quantum-size effects and highly tunable optical properties. Tuning the size of perovskite QDs is attractive for many potential applications. For instance, smaller QDs exhibit more evident quantum properties than larger QDs, but present a blue-shifted spectrum, which limits their applications. Here, we conduct a systematically theoretical analysis about the optical response and plasmon resonance of comparatively small barium titanate quantum dots (BTO–QDs) coupled with silver (Ag) nanowires based on time-dependent density functional theory (TDDFT). Our results show that the silver nanowires can induce an intense optical response respectively in the infrared and visible region to eliminate the spectrum-shift. Furthermore, the absorption spectrum and plasmon resonance can be effectively modified by either altering the position of the silver nanowires or changing the thickness of the BTO–QDs. More importantly, these two methods can act simultaneously, this maybe provide a new approach to implementing the quantum control.</jats:p>

<jats:p>Displacement damage induced by neutron irradiation in China Spallation Neutron Source (CSNS) is studied on bipolar transistors with lateral PNP, substrate PNP, and vertical NPN configurations, respectively. Comparison of the effects on different type transistors is conducted based on displacement damage factor, and the differences are analyzed through minority carrier lifetime calculation and structure analysis. The influence of CSNS neutrons irradiation on the lateral PNP transistors is analyzed by the gate-controlled method, including the oxide charge accumulation, surface recombine velocity, and minority carrier lifetime. The results indicate that the total ionizing dose in CSNS neutron radiation environment is negligible in this study. The displacement damage factors based on 1-MeV equivalent neutron flux of different transistors are consistent between Xi’an pulse reactor (XAPR) and CSNS.</jats:p>

<jats:p>For the numerical simulation of the fractional quantum Hall (FQH) effects on a finite disk, the rotational symmetry is the only symmetry that is used in diagonalizing the Hamiltonian. In this work, we propose a method of using the weak translational symmetry for the center of mass of the many-body system. With this approach, the bulk properties, such as the energy gap and the magneto-roton excitation are consistent with those in the closed manifolds like the sphere and torus. As an application, we consider the FQH phase and its phase transition in the fast rotated dipolar fermions. We thus demonstrate the disk geometry having versatility in analyzing the bulk properties beside the usual edge physics.</jats:p>

<jats:p>In this paper, the interface states of the AlGaN/GaN metal–insulator–semiconductor (MIS) high electron mobility transistors (HEMTs) with an Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> gate dielectric are systematically evaluated. By frequency-dependent capacitance and conductance measurements, trap density and time constant at Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/AlGaN and AlGaN/GaN interface are determined. The experimental results reveal that the density of trap states and the activation energy at the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/AlGaN interface are much higher than at the AlGaN/GaN interface. The photo-assisted capacitance-voltage measurements are performed to characterize the deep-level traps located near mid-gap at the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/AlGaN interface, which indicates that a density of deep-level traps is lower than the density of the shallow-level states.</jats:p>

<jats:p>GaN-based yellow light-emitting diodes (LEDs) on Si substrates are aged at a direct current density of 50 A/cm<jats:sup>2</jats:sup> for 500 h. After the aging process, it can be found that the LEDs have a stable electrical property but their light output power is decayed by 4.01% at 35 A/cm<jats:sup>2</jats:sup>. Additionally, the aging mechanism of GaN-based yellow LED is analyzed. It is found that the decay of light output power may be attributed to the following two reasons: one is the increase of Shockley–Rrad–Hall recombination and the other is the change of the transport path of holes via V-pits after aging, which may induce the radiative recombination current to decrease. In this paper, not only the aging mechanism of GaN-based yellow LED is investigated, but also a new possible research direction in LED aging is given.</jats:p>

<jats:p>Heavy electron-doped FeSe-derived materials have attracted attention due to their uncommon electronic structures with only ‘electron pockets’, and they are different from other iron-based superconductors. Here, we report the crystal structures, superconductivities and normal state properties of two new Li-doped FeSe-based materials, <jats:italic>i.e.</jats:italic>, Li<jats:sub>0.15</jats:sub>(C<jats:sub>3</jats:sub>H<jats:sub>10</jats:sub>N<jats:sub>2</jats:sub>)<jats:sub>0.32</jats:sub>FeSe (<jats:italic>P</jats:italic>-4) and Li<jats:sub> <jats:italic>x</jats:italic> </jats:sub>(C<jats:sub>3</jats:sub>H<jats:sub>10</jats:sub>N<jats:sub>2</jats:sub>)<jats:sub>0.32</jats:sub>FeSe (<jats:italic>P</jats:italic>4/<jats:italic>nmm</jats:italic>, <jats:inline-formula> <jats:tex-math> <?CDATA $0.25\lt x\lt 0.4$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.25</mml:mn> <mml:mo>&lt;</mml:mo> <mml:mi>x</mml:mi> <mml:mo>&lt;</mml:mo> <mml:mn>0.4</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067401_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>) with superconducting transition temperatures ranging from 40 K to 46 K. The determined crystal structures reveal a coupling between Li concentration and the orientation of 1,3-diaminopropane molecules within the largely expanded FeSe layers. Superconducting fluctuations appear in the resistivity of the two superconductors and are fitted in terms of the quasi two-dimensional (2D) Lawrence–Doniach model. The existence of a crossing point and scaling behavior in the <jats:italic>T</jats:italic>-dependence of diamagnetic response also suggests that the two superconductors belong to the quasi-2D system. Interestingly, with the increase of temperature, a sign of Hall coefficient (<jats:italic>R</jats:italic> <jats:sub>H</jats:sub>) reversing from negative to positive is observed at ∼185 K in both phases, suggesting that ‘hole pockets’ emerge in these electron-doped FeSe materials. First principle calculations indicate that the increase in FeSe layer distance will lift up a ‘hole band’ associated with <jats:inline-formula> <jats:tex-math> <?CDATA ${d}_{{x}^{2}-{y}^{2}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>d</mml:mi> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>x</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mo>−</mml:mo> <mml:msup> <mml:mrow> <mml:mi>y</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067401_ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> character and increase the hole carriers. Our findings suggest that the increase in two dimensionalities may lead to the sign-reversal Hall resistivity in Li<jats:sub> <jats:italic>x</jats:italic> </jats:sub>(C<jats:sub>3</jats:sub>H<jats:sub>10</jats:sub>N<jats:sub>2</jats:sub>)<jats:sub>0.32</jats:sub>FeSe at high temperature.</jats:p>

<jats:p>In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa<jats:sub>2</jats:sub>Cu<jats:sub>3</jats:sub>O<jats:sub>7-<jats:italic>δ</jats:italic> </jats:sub> (YBCO) films grown on single-crystal (001) SrTiO<jats:sub>3</jats:sub> substrates. Nearly atomic-flat YBCO films are obtained by pulsed laser deposition. Our result shows that the termination of SrTiO<jats:sub>3</jats:sub> has only a negligible effect on the properties of YBCO. In contrast, we found that capping a non-superconducting oxide layer can generally enhance the superconductivity of YBCO. PrBa<jats:sub>2</jats:sub>Cu<jats:sub>3</jats:sub>O<jats:sub>7</jats:sub>, La<jats:sub>2</jats:sub>CuO<jats:sub>4</jats:sub>, LaMnO<jats:sub>3</jats:sub>, SrTiO<jats:sub>3</jats:sub>, and LaAlO<jats:sub>3</jats:sub> have been examined as capping layers, and the minimum thickness of superconducting YBCO with capping is ∼2 unit cells–3 unit cells. This result might be useful in constructing good-performance YBCO-based field effect devices.</jats:p>

<jats:p>Topological superconductors carry globally protected gapless boundary excitations, which are robust under local perturbations, and thus exhibit both fundamental and applicational importance. An unconventional pairing with p-wave symmetry, such as a nontrivial topology in the superconductor’s wavefunction, is required to generate a non-zero Berry phase. Until now, the Bi<jats:sub>2</jats:sub>Te<jats:sub>3</jats:sub>/2H–NbSe<jats:sub>2</jats:sub> heterostructure has proven to be a practical way to realize a topological superconductor in real materials. This complex system, where odd numbers of spin-momentum locked Dirac cone surface states on the topological insulator Bi<jats:sub>2</jats:sub>Te<jats:sub>3</jats:sub> become superconducting, induced by the proximate effect from the underlying s-wave superconductor 2H–NbSe<jats:sub>2</jats:sub>, realizes an effective two-dimensional (2D) spinless <jats:inline-formula> <jats:tex-math> <?CDATA ${p}_{x}+{\rm{i}}{p}_{y}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>p</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:mo>+</mml:mo> <mml:mi mathvariant="normal">i</mml:mi> <mml:msub> <mml:mrow> <mml:mi>p</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>y</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067403_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> topological superconductor. In this review article, we summarize the recent experimental progress of the successful synthesis of Bi<jats:sub>2</jats:sub>Te<jats:sub>3</jats:sub>/2H–NbSe<jats:sub>2</jats:sub> heterostructures using molecular beam epitaxy, determining the thickness limit of the heterostructure, detecting the long thought Majorana quasiparticle inside a magnetic vortex core state by means of scanning tunneling microscopy and demonstration of the unique spatial and spin properties of a Majorana zero mode.</jats:p>

<jats:p>We investigate the critical exponents and magnetocaloric effect of Co<jats:sub>2−<jats:italic>x</jats:italic> </jats:sub>ZrSn polycrystal. The Co<jats:sub>2−<jats:italic>x</jats:italic> </jats:sub>ZrSn undergoes a second-order ferromagnetism phase transition around the Curie temperature of <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> ∼280 K. The critical behavior in the vicinity of the magnetic phase transition has been investigated by using modified Arrott plot and Kouvel–Fisher methods. The obtained critical exponents, <jats:italic>β</jats:italic>, <jats:italic>γ</jats:italic>, and <jats:italic>δ</jats:italic> can be well described by the scaling theory. The determined exponents of Co<jats:sub>2−<jats:italic>x</jats:italic> </jats:sub>ZrSn obey the mean-field model with a long-range magnetic interaction. In addition, the maximum magnetic entropy change <jats:inline-formula> <jats:tex-math> <?CDATA $-{\rm{\Delta }}{S}_{{\rm{M}}}^{\max }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>−</mml:mo> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:msubsup> <mml:mrow> <mml:mi>S</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>max</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067501_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> of Co<jats:sub>2−<jats:italic>x</jats:italic> </jats:sub>ZrSn is about <jats:inline-formula> <jats:tex-math> <?CDATA $0.57\,{\rm{J}}\cdot {\mathrm{kg}}^{-1}\cdot {{\rm{K}}}^{-1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.57</mml:mn> <mml:mspace width="0.25em" /> <mml:mi mathvariant="normal">J</mml:mi> <mml:mo>·</mml:mo> <mml:msup> <mml:mrow> <mml:mi>kg</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mo>·</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">K</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067501_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> and the relative cooling power (RCP) is <jats:inline-formula> <jats:tex-math> <?CDATA $14.68\,{\rm{J}}\cdot {\mathrm{kg}}^{-1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>14.68</mml:mn> <mml:mspace width="0.25em" /> <mml:mi mathvariant="normal">J</mml:mi> <mml:mo>·</mml:mo> <mml:msup> <mml:mrow> <mml:mi>kg</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067501_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> at 50 kOe (<jats:inline-formula> <jats:tex-math> <?CDATA $1\,\mathrm{Oe}=79.5775\,{\rm{A}}\cdot {{\rm{m}}}^{-1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mspace width="0.25em" /> <mml:mi>Oe</mml:mi> <mml:mo>=</mml:mo> <mml:mn>79.5775</mml:mn> <mml:mspace width="0.25em" /> <mml:mi mathvariant="normal">A</mml:mi> <mml:mo>·</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067501_ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>).</jats:p>

<jats:p>One-port surface acoustic wave resonators (SAWRs) are fabricated on semi-insulating high-quality bulk GaN and GaN film substrates, respectively. The semi-insulating GaN substrates are grown by hydride vapor phase epitaxy (HVPE) and doped with Fe. The anisotropy of Rayleigh propagation and the electromechanical coupling coefficient in Fe-doped GaN are investigated. The difference in resonance frequency between the SAWs between [11 <jats:inline-formula> <jats:tex-math><?CDATA $\bar{2}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067701_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> 0] GaN and [1 <jats:inline-formula> <jats:tex-math><?CDATA $\bar{1}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067701_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> 00] GaN is about 0.25% for the Rayleigh propagation mode, which is smaller than that of non-intentionally doped GaN film (̃1%) reported in the literature. The electromechanical coupling coefficient of Fe-doped GaN is about 3.03%, which is higher than that of non-intentionally doped GaN film. The one-port SAWR fabricated on an 8-<jats:inline-formula> <jats:tex-math><?CDATA ${\rm{\mu }}{\rm{m}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_6_067701_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> Fe-doped GaN/sapphire substrate has a quality factor of 2050, and that fabricated on Fe-doped bulk GaN has a quality factor as high as 3650. All of our results indicate that high-quality bulk GaN is a very promising material for application in SAW devices.</jats:p>