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<jats:p>The anisotropic magnetoresistances (AMRs) in single crystalline Co(6 nm)/SrTiO<jats:sub>3</jats:sub>(001) heterostructures from 5 K to 300 K with the current direction setting along either Co[100] or Co[110] are investigated in this work. The anomalous (normal) AMR is observed below (above) 100 K. With the current along Co[100] direction, the AMR shows negative longitudinal and positive transverse magnetoresistances at <jats:italic>T</jats:italic> &lt; 100 K, while the AMR is inverse with the current along Co[110]. Meanwhile, the amplitude ratio between Co[110] and Co[100] is observed to be as large as 29 at 100 K. A crystal symmetry-adapted model of AMR demonstrates that interplay between the non-crystalline component and crossed AMR component results in the anomalous AMR. Our results may reveal more intriguing magneto-transport behaviors of film on SrTiO<jats:sub>3</jats:sub> or other perovskite oxides.</jats:p>

<jats:p>A strong chiral near-field plays significant roles in the detection, separation and sensing of chiral molecules. In this paper, a simple and symmetric metasurface is proposed to generate strong chiral near-fields with both circularly polarized light and linearly polarized light illuminations in the mid-infrared region. Owing to the near-field interaction between plasmonic resonant modes of two nanosheets excited by circularly polarized light, there is a strong single-handed chiral near-field in the gap between the two graphene nanosheets and the maximum enhancement of the optical chirality could reach two orders of magnitude. As expected, the intensity and the response wavelength of the chiral near-fields could be controlled by the Fermi level and geometrical parameters of the graphene nanosheets, as well as the permittivity of the substrate. Meanwhile, based on the interaction between the incident field and scattered field, the one-handed chiral near-field in the gap also could be generated by the linearly polarized light excitation. For the two cases, the handedness of the chiral near-field could be switched by the polarized direction of the incident light. These results have potential opportunities for applications in molecular detection and sensing.</jats:p>

<jats:p>The interaction between a permanent magnet (PM) assumed as a magnetic dipole and a flat high-temperature superconductor (HTS) is calculated by the advanced frozen-image model. When the dipole vertically moves above the semi-infinite HTS, the general analytical expression of vertical force and that of torque are obtained for an arbitrary angle between the magnetization direction of the PM and the <jats:italic>c</jats:italic> axis of the HTS. The variations of the force and torque are analyzed for angle and vertical movements in both zero-field cooling (ZFC) condition and field cooling (FC) condition. It is found that the maximum vertical repulsive or attractive force has the positive or negative cosine relation with the angle. However, the maximum torque has the positive or negative sine relation. From the viewpoint of the rotational equilibrium, the orientation of the magnetic dipole with zero angle is deemed to be an unstable equilibrium point in ZFC, but the same orientation is considered as a stable equilibrium point in FC. In addition, both of the variation cycles of the maximum force and torque with the angle are <jats:italic>π</jats:italic>.</jats:p>

<jats:p>We report an inelastic neutron scattering investigation on the spin resonance mode in the optimally hole-doped iron-based superconductor Ba<jats:sub>0.67</jats:sub>K<jats:sub>0.33</jats:sub>Fe<jats:sub>2</jats:sub>As<jats:sub>2</jats:sub> with <jats:italic>T<jats:sub>c</jats:sub>=</jats:italic> 38.2 K. Although the resonance is nearly two-dimensional with peak energy <jats:italic>E</jats:italic> <jats:sub>R</jats:sub> ≈ 14 meV, it splits into two incommensurate peaks along the longitudinal direction ([<jats:italic>H</jats:italic>,0,0]) and shows an upward dispersion persisting to 26 meV. Such dispersion breaks through the limit of total superconducting gaps <jats:italic>Δ</jats:italic> <jats:sub>tot</jats:sub> = |<jats:italic>Δ<jats:sub>k</jats:sub> </jats:italic> | + |<jats:italic>Δ</jats:italic> <jats:sub> <jats:italic>k</jats:italic>+<jats:italic>Q</jats:italic> </jats:sub>| (about 11–17 meV) on nested Fermi surfaces measured by high resolution angle resolved photoemission spectroscopy (ARPES). These results cannot be fully understood by the magnetic exciton scenario under s<jats:sup>±</jats:sup>-pairing symmetry of superconductivity, and suggest that the spin resonance may not be restricted by the superconducting gaps in the multi-band systems.</jats:p>

<jats:p>We theoretically provide a magnetic phase diagram for the single-layer (SL) CrBr<jats:sub>3</jats:sub>, which could be effectively tuned by both strain engineering and charge doping in SL-CrBr<jats:sub>3</jats:sub>. Through systematical first-principles calculations and Heisenberg model Hamiltonian simulations, three different magnetic phases in SL-CrBr<jats:sub>3</jats:sub>, which are off-plane ferromagnetic, in-plane ferromagnetic and in-plane Néel-antiferromagnetic phases, are found in the strain and charge doping regimes we studied. Furthermore, our results show that higher order Heisenberg exchange parameters and anisotropy exchange parameters should be taken into account for accurately illustrating the magnetic phase transition in SL-CrBr<jats:sub>3</jats:sub>. As a result, we find from the SpinW simulation that the Curie temperature is about <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> = 38.4 K, which is well consistent with the experimental result 34 K [<jats:italic>Nano Lett.</jats:italic> <jats:bold>19</jats:bold> 3138 (2019)]. The findings here may be confirmed in future experiments, and may be useful for the potential applications of SL-CrBr<jats:sub>3</jats:sub> in spintronics field.</jats:p>

<jats:p>The magnetic anisotropy manipulation in the Sm<jats:sub>3</jats:sub>Fe<jats:sub>5</jats:sub>O<jats:sub>12</jats:sub> (SmIG) films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully. By switching the orientation of the Gd<jats:sub>3</jats:sub>Ga<jats:sub>5</jats:sub>O<jats:sub>12</jats:sub> substrates from (111) to (001), the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane. Similar results can also be obtained in the films on Gd<jats:sub>3</jats:sub>Sc<jats:sub>2</jats:sub>Ga<jats:sub>3</jats:sub>O<jats:sub>12</jats:sub> substrates, which identifies the universality of such orientation-induced magnetic anisotropy switching. Additionally, the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto–optical Kerr effect technique. It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films. These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.</jats:p>

<jats:p>We study the influence of the thermodynamic coefficients on transient negative capacitance for the Zr-doped HfO<jats:sub>2</jats:sub> (HZO) ferroelectric capacitors by the theoretical simulation based on the Landau–Khalatnikov (L-K) theory and experimental measurement of electrical properties in the resistor-ferroelectric capacitor (<jats:italic>R</jats:italic>-FEC) circuit. Our results show that the thermodynamic coefficients <jats:italic>α</jats:italic>, <jats:italic>β</jats:italic> and <jats:italic>γ</jats:italic> also play a key role for the transient NC effect besides the viscosity coefficient and series resistor. Moreover, the smaller coefficients <jats:italic>α</jats:italic> and <jats:italic>β</jats:italic>, the more significant the transient NC effect. In addition, we also find that the thermodynamic process of transient NC does not obey the generally accepted viewpoint of Gibbs free energy minimization.</jats:p>

<jats:p>The chemical reaction products of elemental sulfur (S), selenium (Se), and molecular hydrogen (H<jats:sub>2</jats:sub>) at high pressures and room temperature are probed by Raman spectroscopy. Two known compounds H<jats:sub>2</jats:sub>S and H<jats:sub>2</jats:sub>Se can be synthesized after laser heating at pressures lower than 1 GPa. Under further compression at room temperature, an H<jats:sub>2</jats:sub>S–H<jats:sub>2</jats:sub>Se and an H<jats:sub>2</jats:sub>S–H<jats:sub>2</jats:sub>Se–H<jats:sub>2</jats:sub> van der Waals compounds are synthesized at 4 GPa and 6 GPa, respectively. The later is of guest–host structure and can be identified as (H<jats:sub>2</jats:sub>S)<jats:sub> <jats:italic>x</jats:italic> </jats:sub>(H<jats:sub>2</jats:sub>Se)<jats:sub>(2−<jats:italic>x</jats:italic>)</jats:sub>H<jats:sub>2</jats:sub>. It can be maintained up to 37 GPa at least, and the stability of its H<jats:sub>2</jats:sub>Se molecules is extended: the H–Se stretching mode can be detected at least to 36 GPa but disappears at 22 GPa in (H<jats:sub>2</jats:sub>Se)<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>. The pressure dependence of S–H and Se–H stretching modes of this ternary compound is in line with that of (H<jats:sub>2</jats:sub>S)<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub> and (H<jats:sub>2</jats:sub>Se)<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>, respectively. However, its hydrogen subsystem only shows the relevance to (H<jats:sub>2</jats:sub>S)<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>, indicating that this ternary compound can be viewed as H<jats:sub>2</jats:sub>Se-replaced partial H<jats:sub>2</jats:sub>S of (H<jats:sub>2</jats:sub>S)<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>.</jats:p>

<jats:p>Improving the emission performance of colloidal quantum dots (QDs) is of paramount importance for their applications on light-emitting diodes (LEDs), displays and lasers. A highly promising approach is to tune the carrier recombination channels and lifetime by exploiting the energy transfer process. However, to achieve this precise emission optimization, quantitative modulation on energy transfer efficiency is highly desirable but still challenging. Here, we demonstrate a convenient approach to realize tunable energy transfer efficiency by forming QDs mixture with controllable donor/acceptor (D/A) ratio. With the mixing ratio ranging from 16/1 to 1/16, the energy transfer efficiency could be effectively tuned from near zero to ∼ 70%. For the high mixing ratio of 16/1, acceptors obtain adequate energy supplied by closely surrounding donors, leading to ∼ 2.4-fold PL enhancement. While for the low mixing ratio, the ultrafast and efficient energy extraction process directly suppresses the multi-exciton and Auger recombination in the donor, bringing about a higher threshold. The facile modulation of emission performance by controllably designed mixing ratio and quantitatively tunable energy transfer efficiency will facilitate QD-based optoelectronic and photovoltaic applications.</jats:p>

<jats:p>We present a high-efficiency tunable wide-angle multi-band reflective linear-to-linear (LTL) polarization converter, which is composed of an array of two L-shaped graphene patches with different sizes. In the mid-infrared region, the proposed converter can transform <jats:italic>x</jats:italic>-polarized wave into <jats:italic>y</jats:italic>-polarized wave at four resonant frequencies. The polarization conversion ratios of the four bands reach 94.4%, 92.7%, 99.3%, and 93.1%, respectively. By carefully choosing the geometric parameter, triple-band LTL polarization conversion can also be realized. The three polarization conversion ratios reach 91.50%, 99.20%, and 97.22%, respectively. The influence of incident angle on the performances of the LTL polarization converter is investigated, and it is found that our polarization converter shows the angle insensitivity. Also, the dynamically tunable properties of the proposed polarization converter are numerically studied by changing Fermi energy. All the simulation results are conducted by finite element method.</jats:p>