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<jats:p>Bulk SnSe is an excellent thermoelectrical material with the highest figure-of-merit value of <jats:italic>ZT</jats:italic> = 2.8, making it promising in applications. Temperature-dependent electrical and thermoelectrical properties of SnSe nanoplates are studied at low temperature. Conductivity drops and rises again as temperature is lowered. The Seebeck coefficient is positive at room temperature and becomes negative at low temperature. The change of the sign of the Seebeck coefficient indicates influence of bipolar transport of the semiconductive SnSe nanoplate. The bipolar transport is caused by the Fermi energy changing with temperature due to different contributions from donors and acceptors at different temperatures.</jats:p>

<jats:p>We have successfully synthesized two novel compounds [<jats:italic>A</jats:italic> <jats:sub>6</jats:sub>Cl][Fe<jats:sub>24</jats:sub>Se<jats:sub>26</jats:sub>] (<jats:italic>A</jats:italic> = K, Rb). The key structural units of them are FeSe octamers, consisting of edge-shared FeSe<jats:sub>4</jats:sub> tetrahedra. Two kinds of FeSe octamer layers with different connection configurations stack along the <jats:italic>c</jats:italic> axis, forming a three-dimensional (3D) TiAl<jats:sub>3</jats:sub>-type structure. Interestingly, the 3D structural topology of these ocatmers in one unit cell is similar to the local atomic arrangement of themselves, i.e., self-similarity in structure. Physical property characterizations indicate that both the compounds exhibit insulating antiferromagnetism with Neel temperatures <jats:italic>T</jats:italic> <jats:sub>N</jats:sub> ∼ 110 K and 75 K for [K<jats:sub>6</jats:sub>Cl][Fe<jats:sub>24</jats:sub>Se<jats:sub>26</jats:sub>] and [Rb<jats:sub>6</jats:sub>Cl][Fe<jats:sub>24</jats:sub>Se<jats:sub>26</jats:sub>].</jats:p>

<jats:p>We report high-resolution scanning tunneling microscopy (STM) study of nano-sized Pb islands grown on SrTiO<jats:sub>3</jats:sub>, where three distinct types of gaps with different energy scales are revealed. At low temperature, we find that the superconducting gap (<jats:italic>Δ</jats:italic> <jats:sub>s</jats:sub>) in nano-sized Pb islands is significantly enhanced from the one in bulk Pb, while there is no essential change in superconducting transition temperature <jats:italic>T</jats:italic> <jats:sub>c</jats:sub>, giving rise to a larger BCS ratio 2<jats:italic>Δ</jats:italic> <jats:sub>s</jats:sub>/<jats:italic>k</jats:italic> <jats:sub> <jats:sub>B</jats:sub> </jats:sub> <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> ∼ 8.31 and implying stronger electron-phonon coupling. The stronger coupling can originate from the interface electron-phonon interactions between Pb islands and SrTiO<jats:sub>3</jats:sub>. As the superconducting gap is totally suppressed under applied magnetic field, the Coulomb gap with apparent V-shape emerges. Moreover, the size of Coulomb gap (<jats:italic>Δ</jats:italic> <jats:sub>C</jats:sub>) depends on the lateral size of Pb islands (<jats:italic>R</jats:italic>) with <jats:italic>Δ</jats:italic> <jats:sub>C</jats:sub> ∼ 1/<jats:italic>R</jats:italic> <jats:sup>0.35</jats:sup>, indicating that quantum size effect can significantly influence electronic correlations. Our experimental results shall shed important light on the interplay among superconductivity, quantum size effect and correlations in nano-sized strong-coupling superconductors.</jats:p>

<jats:p>We investigate in underdoped cuprates possible coexistence of the superconducting order at zero momentum and pair density wave (PDW) at momentum <jats:italic> <jats:bold>Q</jats:bold> </jats:italic> = (<jats:italic>π</jats:italic>, <jats:italic>π</jats:italic>) in the presence of a Néel order. By symmetry, the d-wave uniform singlet pairing <jats:italic>dS</jats:italic> <jats:sub>0</jats:sub> can coexist with the d-wave triplet PDW <jats:italic>dT</jats:italic> <jats:sub> <jats:bold>Q</jats:bold> </jats:sub>, and the p-wave singlet PDW <jats:italic>p</jats:italic> <jats:sub> <jats:italic> <jats:bold>Q</jats:bold> </jats:italic> </jats:sub> can coexist with the p-wave uniform triplet <jats:italic>pT</jats:italic> <jats:sub>0</jats:sub>. At half filling, we find that the novel <jats:italic>pS</jats:italic> <jats:sub> <jats:bold>Q</jats:bold> </jats:sub>+ <jats:italic>pT</jats:italic> <jats:sub>0</jats:sub> state is energetically more favorable than the <jats:italic>dS</jats:italic> <jats:sub>0</jats:sub> + <jats:italic>dT</jats:italic> <jats:sub> <jats:italic> <jats:bold>Q</jats:bold> </jats:italic> </jats:sub> state. At finite doping, however, the <jats:italic>dS</jats:italic> <jats:sub>0</jats:sub> + <jats:italic>dT</jats:italic> <jats:sub> <jats:italic> <jats:bold>Q</jats:bold> </jats:italic> </jats:sub> state is more favorable. In both types of states, the variational triplet parameters <jats:italic>dT</jats:italic> <jats:sub> <jats:italic> <jats:bold>Q</jats:bold> </jats:italic> </jats:sub> and <jats:italic>pT</jats:italic> <jats:sub>0</jats:sub> are of secondary significance. Our results point to a fully symmetric Z<jats:sub>2</jats:sub> quantum spin liquid with spinon Fermi surface in proximity to the Néel order at zero doping, which may not be adiabatically connected to the d-wave singlet superconductivity at finite doping with intertwining d-wave triplet PDW fluctuations and spin moment fluctuations. The results are obtained by variational quantum Monte Carlo simulations.</jats:p>

<jats:p>Magnetic properties and the magnetocaloric effect (MCE) of the <jats:italic>R</jats:italic>Si (<jats:italic>R</jats:italic> = Ce, Pr, Nd) compounds made of Misch metal (MM) are investigated. Two transitions are found at 12 K and 38 K. Field variation generated large MCE and two peaks are found in the magnetic entropy change (Δ<jats:italic>S</jats:italic>) curves, which correspond to the two transition temperatures. The maximum values of the magnetic entropy changes (Δ<jats:italic>S</jats:italic>) are found to be −5.1 J/(kg⋅K) and −9.3 J/(kg⋅K) for the field ranges of 0–2 T and 0–5 T, respectively. The large Δ<jats:italic>S</jats:italic> as well as ultra-low price of MM make (MM)Si a competitive magnetic refrigerant candidate for low temperature in Eriksson cycle.</jats:p>

<jats:p> <jats:italic>The collective modes of two-dimensional helical electron gases interacting with light have been studied in an extended random phase approximation. An inverse operator transformation that interprets electron oscillations and photons with quasi particles is developed. Because photons are initially included in the model, one can directly derive and compare the static and radiation (or vector) fields for the excited collective modes. Unlike the traditional quantization scheme that the electron oscillation’s contribution is totally hidden in the dielectric function, we can directly investigate their roles when the collective modes interact with other particles. As an example, we find an additional term which plays an important role at small distance arising from electron exchanging effect when the collective modes couple to emitters</jats:italic>.</jats:p>

<jats:p>Semiconductors grown by the solution-processed method have shown low-cost, facile fabrication process and comparable performance. However, there are many reasons why it is difficult to achieve high quality films. For example, lattice constant mismatch is one of the problems when photovoltaic devices made of organ metallic perovskites. In this work, <jats:italic>MA</jats:italic>PbBr<jats:sub>3</jats:sub> (<jats:inline-formula> <jats:tex-math> <?CDATA $MA=C{H}_{3}N{H}_{3}^{+}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>M</mml:mi> <mml:mi>A</mml:mi> <mml:mo>=</mml:mo> <mml:mi>C</mml:mi> <mml:msub> <mml:mi>H</mml:mi> <mml:mn>3</mml:mn> </mml:msub> <mml:mi>N</mml:mi> <mml:msubsup> <mml:mi>H</mml:mi> <mml:mn>3</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="cpl_37_1_018101_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) perovskites single crystals grown on the surface of <jats:italic>MA</jats:italic>PbBr<jats:sub>2.5</jats:sub>Cl<jats:sub>0.5</jats:sub> perovskites single crystals via liquid epitaxial growth method is demonstrated. It is found that when the lattice constants of the two perovskite single crystals are matched, another crystal can be grown on the surface of one crystal by epitaxial growth. The whole epitaxy growth process does not require high heating temperature and long heating time. X-ray diffraction method is used to prove the lattice plane of the substrate and the epitaxial grown layer. A scanning electron microscope is used to measure the thickness of the epitaxial layer. Compared with perovskite-based photodetectors without epitaxial growth layer, perovskite-based photodetectors with epitaxial growth layer have lower dark current density and higher optical responsibility.</jats:p>

<jats:p>Advanced machine learning (ML) approaches such as transfer learning have seldom been applied to approximate quantum many-body systems. Here we demonstrate that a simple recurrent unit (SRU) based efficient and transferable sequence learning framework is capable of learning and accurately predicting the time evolution of the one-dimensional (1D) Ising model with simultaneous transverse and parallel magnetic fields, as quantitatively corroborated by relative entropy measurements between the predicted and exact state distributions. At a cost of constant computational complexity, a larger many-body state evolution is predicted in an autoregressive way from just one initial state, without any guidance or knowledge of any Hamiltonian. Our work paves the way for future applications of advanced ML methods in quantum many-body dynamics with knowledge only from a smaller system.</jats:p>

<jats:p> <jats:italic>Recently, there are great efforts that have been taken to suppressing/controlling the coffee ring effect, but it is of challenge to achieve inexpensive and efficient control with less disturbance, suitable for scalable production and highly enhancing the printing/dyeing color fastness. By only adding trace amounts of salt into the suspensions, here we experimentally achieve the facile and highly efficient control of the coffee ring effect of suspended matter on substrates of graphene, natural graphite, and polyethylene terephthalate surfaces. Notably, friction force measurements show that ion-controlled uniform patterns also greatly enhance color fastness. Molecular dynamics simulations reveal that, due to strong hydrated cation-<jats:italic>π</jats:italic> interactions between hydrated cations and aromatic rings in the substrate surface, the suspended matters are adsorbed on the surfaces mediated by cations so that the suspended matters are uniformly distributed. These findings will open new avenues for fabricating functional patterns on graphene substrates and will benefit practical applications including printing, coating, and dyeing.</jats:italic> </jats:p>