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<jats:p> <jats:italic>We report a comprehensive high-pressure study on the monoclinic TlFeSe<jats:sub>2</jats:sub> single crystal, which is an antiferromagnetic insulator with quasi-one-dimensional crystal structure at ambient pressure. It is found that TlFeSe<jats:sub>2</jats:sub> undergoes a pressure-induced structural transformation from the monoclinic phase to an orthorhombic structure above <jats:italic>P</jats:italic> <jats:sub>c</jats:sub> ≈ 13 GPa, accompanied with a large volume collapse of Δ<jats:italic>V</jats:italic>/<jats:italic>V</jats:italic> <jats:sub>0</jats:sub> = 8.3%. In the low-pressure monoclinic phase, the insulating state is easily metallized at pressures above 2 GPa; while possible superconductivity with <jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{{\rm{c}}}^{{\rm{onset}}}\sim 2$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>T</mml:mi> <mml:mi mathvariant="normal">c</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">onset</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>∼</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_37_4_047102_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> K is found to emerge above 30 GPa in the high-pressure phase. Such a great tunability of TlFeSe<jats:sub>2</jats:sub> under pressure indicates that the ternary <jats:italic>A</jats:italic>FeSe<jats:sub>2</jats:sub> system (<jats:italic>A</jats:italic> = Tl, K, Cs, Rb) should be taken as an important platform for explorations of interesting phenomena such as insulator-metal transition, dimensionality crossover, and superconductivity</jats:italic>.</jats:p>

<jats:p> <jats:italic>Orthogonal metal is a new quantum metallic state that conducts electricity but acquires no Fermi surface (FS) or quasiparticles, and hence orthogonal to the established paradigm of Landau’s Fermi-liquid (FL). Such a state may hold the key of understanding the perplexing experimental observations of quantum metals that are beyond FL, i.e., dubbed non-Fermi-liquid (nFL), ranging from the Cu- and Fe-based oxides, heavy fermion compounds to the recently discovered twisted graphene heterostructures. However, to fully understand such an exotic state of matter, at least theoretically, one would like to construct a lattice model and to solve it with unbiased quantum many-body machinery. Here we achieve this goal by designing a 2D lattice model comprised of fermionic and bosonic matter fields coupled with dynamic ℤ<jats:sub>2</jats:sub> gauge fields, and obtain its exact properties with sign-free quantum Monte Carlo simulations. We find that as the bosonic matter fields become disordered, with the help of deconfinement of the ℤ<jats:sub>2</jats:sub> gauge fields, the system reacts with changing its nature from the conventional normal metal with an FS to an orthogonal metal of nFL without FS and quasiparticles and yet still responds to magnetic probe like an FL. Such a quantum phase transition from a normal metal to an orthogonal metal, with its electronic and magnetic spectral properties revealed, is calling for the establishment of new paradigm of quantum metals and their transition with conventional ones</jats:italic>.</jats:p>

<jats:p> <jats:italic>The measurements of magnetization, longitudinal and Hall resistivities are carried out on the intrinsic antiferromagnetic (AFM) topological insulator EuSn</jats:italic> <jats:sub>2</jats:sub> <jats:italic>As</jats:italic> <jats:sub>2</jats:sub>. <jats:italic>It is confirmed that our EuSn</jats:italic> <jats:sub>2</jats:sub> <jats:italic>As</jats:italic> <jats:sub>2</jats:sub> <jats:italic>crystal is a heavily hole doping A-type AFM metal with the Néel temperature T</jats:italic> <jats:sub>N</jats:sub> = <jats:italic>24 K, with a metamagnetic transition from an AFM to a ferromagnetic (FM) phase occurring at a certain critical magnetic field for the different field orientations. Meanwhile, we also find that the carrier concentration does not change with the evolution of magnetic order, indicating that the weak interaction between the localized magnetic moments from Eu</jats:italic> <jats:sup>2+</jats:sup> 4<jats:italic>f</jats:italic> <jats:sup>7</jats:sup> <jats:italic>orbits and the electronic states near the Fermi level. Although the quantum anomalous Hall effect (AHE) is not observed in our crystals, it is found that a relatively large negative magnetoresistance (−13%) emerges in the AFM phase, and exhibits an exponential dependence upon magnetic field, whose microscopic origin is waiting to be clarified in future research.</jats:italic> </jats:p>

<jats:p> <jats:italic>We report on low-temperature electron transport properties of MnSb</jats:italic> <jats:sub>2</jats:sub> <jats:italic>Te</jats:italic> <jats:sub>4</jats:sub>, <jats:italic>a candidate of ferrimagnetic Weyl semimetal. Long-range magnetic order is manifested as a nearly square-shaped hysteresis loop in the anomalous Hall resistance, as well as sharp jumps in the magnetoresistance. At temperatures below 4 K, a</jats:italic> ln<jats:italic>T-type upturn appears in the temperature dependence of longitudinal resistance, which can be attributed to the electron-electron interaction (EEI), since the weak localization can be excluded by the temperature dependence of magnetoresistance. Although the anomalous Hall resistance exhibits a similar</jats:italic> ln<jats:italic>T-type upturn in the same temperature range, such correction is absent in the anomalous Hall conductivity. Our work demonstrates that MnSb</jats:italic> <jats:sub>2</jats:sub> <jats:italic>Te</jats:italic> <jats:sub>4</jats:sub> <jats:italic>microflakes provide an ideal system to test the theory of EEI correction to the anomalous Hall effect.</jats:italic> </jats:p>

<jats:p> <jats:italic>By integrating pump-probe ultrafast spectroscopy with diamond anvil cell (DAC) technique, we demonstrate a time-resolved ultrafast dynamics study on non-equilibrium quasiparticle (QP) states in Sr</jats:italic> <jats:sub>2</jats:sub> <jats:italic>IrO</jats:italic> <jats:sub>4</jats:sub> <jats:italic>under high pressure. On-site in situ condition is realized, where both the sample and DAC have fixed position during the experiment. The QP dynamics exhibits a salient pressure-induced phonon bottleneck feature at 20 GPa, which corresponds to a gap shrinkage in the electronic structure. A structural transition is also observed at 32 GPa. In addition, the slowest relaxation component reveals possible heat diffusion or pressure-controlled local spin fluctuation associated with the gap shrinkage. Our work enables precise pressure dependence investigations of ultrafast dynamics, paving the way for reliable studies of high-pressure excited state physics.</jats:italic> </jats:p>

<jats:p> <jats:italic>Non-layered two-dimensional (2D) lead sulfide (PbS) has attracted growing interest recently due to its direct narrow bandgap (0.4 eV) and broad spectral detection from visible to mid-IR region, which lead to remarkable electronic and optoelectronic properties promising for real applications. We report the chemical vapor deposition growth of highly crystalline 2D PbS crystals on mica substrates. The high quality and uniformity of 2D PbS nanoplates are confirmed by atomic force microscopy, x-ray powder diffraction, transmission electron microscopy and x-ray photoelectron spectroscopy. The morphology and lateral size are controllable by different growth temperatures. Photodetectors made from 2D PbS nanoplates reveal good stability, high photoresponsivity, and fast response time, which indicates their promising applications for ultrathin optoelectronics.</jats:italic> </jats:p>

<jats:p> <jats:italic>Methane clathrate hydrate (MCH) is a promising energy resource, but controllable extraction of CH</jats:italic> <jats:sub>4</jats:sub> <jats:italic>from MCH remains a challenge. Gradually replacing CH</jats:italic> <jats:sub>4</jats:sub> <jats:italic>in MCH with CO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>is an attractive scheme, as it is cost efficient and mitigates the environmentally harmful effects of CO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>by sequestration. However, the practicable implementation of this method has not yet been achieved. In this study, using in situ neutron diffraction, we confirm that CH</jats:italic> <jats:sub>4</jats:sub> <jats:italic>in the 5</jats:italic> <jats:sup>12</jats:sup>6<jats:sup>2</jats:sup> <jats:italic>cages of bulk structure-I (sI) MCH can be substituted by gaseous CO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>under high pressure and low temperature with a high substitution ratio (∼44%) while conserving the structure of the hydrate framework. First-principles calculations indicate that CO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>binds more strongly to the 5</jats:italic> <jats:sup>12</jats:sup>6<jats:sup>2</jats:sup> <jats:italic>cages than methane does, and that the diffusion barrier for CH</jats:italic> <jats:sub>4</jats:sub> <jats:italic>is significantly lowered by an intermediate state in which one hydrate cage is doubly occupied by CH</jats:italic> <jats:sub>4</jats:sub> <jats:italic>and CO</jats:italic> <jats:sub>2</jats:sub>. <jats:italic>Therefore, exchange of CO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>for CH</jats:italic> <jats:sub>4</jats:sub> <jats:italic>in MCH is not only energetically favorable but also kinetically feasible. Experimental and theoretical studies of CH</jats:italic> <jats:sub>4</jats:sub>/<jats:italic>CO</jats:italic> <jats:sub>2</jats:sub> <jats:italic>substitution elucidate a method to harness energy from these combustible ice resources.</jats:italic> </jats:p>

<jats:p> <jats:italic>It is difficult to investigate the behavior of solitons in realistic inhomogeneity media in experiment due to inhomogeneity of the media and noise from the unwanted coupling. We propose to use a waveguide-like transmission line which is based on direct-current super-conducting quantum interference devices to simulate behavior of solitons because we find that the behavior of the node flux in this transmission is similar to that of solitons with variable mass.</jats:italic> </jats:p>

<jats:p> <jats:italic>We study the algebraic structure of the one-dimensional Dirac oscillator by extending the concept of spin symmetry to a noncommutative case. An <jats:italic>SO</jats:italic>(4) algebra is found connecting the eigenstates of the Dirac oscillator, in which the two elements of Cartan subalgebra are conserved quantities. Similar results are obtained in the Jaynes–Cummings model.</jats:italic> </jats:p>

<jats:p> <jats:italic>We propose a scenario to increase the probability of probabilistic quantum deletion and to enhance the fidelity of approximate quantum deletion for two non-orthogonal states via weak measurement. More interestingly, by pretreating the given non-orthogonal states, the probability of probabilistic quantum deletion and fidelity of approximate quantum deletion can reach 1. Since outcomes of the weak measurement that we required are probabilistic, we perform the subsequent deleting process only when the outcome of weak measurement is “yes”. Remarkably, we find that our scenario has better performance in quantum information process; for example, it costs less quantum resources and time.</jats:italic> </jats:p>