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Two-dimensional (2D) materials with multiphase, multielement crystals such as transition metal chalcogenides (TMCs) (based on V, Cr, Mn, Fe, Cd, Pt and Pd) and transition metal phosphorous chalcogenides (TMPCs) offer a unique platform to explore novel physical phenomena. However, the synthesis of a single-phase/single-composition crystal of these 2D materials via chemical vapour deposition is still challenging. Here we unravel a competitive-chemical-reaction-based growth mechanism to manipulate the nucleation and growth rate. Based on the growth mechanism, 67 types of TMCs and TMPCs with a defined phase, controllable structure and tunable component can be realized. The ferromagnetism and superconductivity in FeXy can be tuned by the y value, such as superconductivity observed in FeX and ferromagnetism in FeS2 monolayers, demonstrating the high quality of as-grown 2D materials. This work paves the way for the multidisciplinary exploration of 2D TMPCs and TMCs with unique properties. Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This work was supported by the National Key R&D Program of China (grant no. 2020YFA0308800) and the NSF of China (grant nos. 62174013, 11504046 12061131002 and 11734003). This work was also supported by the National Research Foundation— Competitive Research Program (NRF-CRP22-2019-0007, NRF-CRP21-2018-0007 and NRF2020-NRF-ISF004-3520). This work was also supported by the Singapore Ministry of Education Tier 3 Programme ‘Geometrical Quantum Materials’ (MOE2018-T3-1-002), AcRF Tier 2 (MOE2019-T2-2-105) and AcRF Tier 1 RG161/19 and RG7/21. W.B.G. acknowledges the support of NRF CRP by NRF-CRP22-2019-0004. G.L. and L. Lu acknowledge fundings from the National Natural Science Foundation of China under grant numbers 92065203 and 11874406, and the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB33010300). Y.Y. was supported by the National Key R&D Program of China (grant no. 2016YFA0300600). C.Z. acknowledges the Fundamental Research Funds for the central Universities. F.D. and J.D. acknowledge funding from the Institute for Basic Science, Republic of Korea (IBS‐R019‐D1) and the use of the IBS‐CMCM high‐performance computing system Cimulator. This work was also supported by the Innovation Program of Shanghai Municipal Education Commission (no. 2019-01-07-00-09-E00020) and Shanghai Municipal Science and Technology Commission (18JC1412800). Y.-C.L. and K.S. acknowledge JSPS-KAKENHI (JP16H06333 and 18K14119), JSPS A3 Foresight Program and Kazato Research Encouragement Prize. H. Yang acknowledges funding from the Chinese Academy of Sciences (grant nos. XDB33030100). Y.Y. acknowledges the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB30000000).

Topological materials with boundary (surface/edge/hinge) states have attracted tremendous research interest. Besides, unconventional (obstructed atomic) materials have recently drawn lots of attention owing to their obstructed boundary states. Experimentally, Josephson junctions (JJs) constructed on materials with boundary states produce the peculiar boundary supercurrent, which was utilized as a powerful diagnostic approach. Here, we report the observations of conspicuous hinge supercurrent in NiTe$_2$-based JJs. Particularly, applying an in-plane magnetic field along the Josephson current could rapidly suppress the bulk supercurrent and retain the nearly pure hinge supercurrent, namely the magnetic field filtering of supercurrent. Further systematic comparative analysis and theoretical calculations demonstrate the existence of unconventional nature and obstructed hinge states in NiTe$_2$. Our results revealed the unique hinge states in unconventional metal NiTe$_2$, and demonstrated in-plane magnetic field as an efficient method to filter out the futile bulk contributions and thereby to highlight the hinge states hidden in topological/unconventional materials., 20+6 pages,6+5 figures

We demonstrate that superconducting gatemon qubits based on superconductor-semiconductor-superconductor Josephson junctions can be constructed on hole-type Ge/Si core/shell nanowires. The frequency of the qubit can be set firstly by controlling the diffusion of Al in the nanowire via thermal annealing, which yields a suitable critical supercurrent allowing the qubit frequency to be within the experimentally accessible range, and then by fine tuning of a gate voltage, by which an accurate adjustment of the frequency can be realized. On the resulted qubit, Rabi oscillation with an energy relaxation time $${T}_{1} \sim 180\,{\rm{ns}}$$ T 1 ~ 180 ns was observed in the time domain, an average decoherence time $${T}_{2}^{* } \sim 15\,{\rm{ns}}$$ T 2 * ~ 15 ns was obtained, and the gate voltage dependence of both $${T}_{1}$$ T 1 and $${T}_{2}^{* }$$ T 2 * was investigated. Such a hole-type superconducting gatemon qubit, based on materials with strong spin-orbit coupling and potentially the absence of hyperfine interaction after isotope purification, could be used for exploring the quantum coherence phenomena of hole-gas and even Majorana physics in Ge-based quantum devices.

The intercalated iron selenide (Li,Fe)OHFeSe has a strongly layered structure analogous to the quasi two-dimensional (2D) bismuth cuprate superconductors, and exhibits both high-temperature (Tc) and topological superconductivity. However, the issue of its superconductivity dimensionality has not yet been fully investigated so far. Here we report that the quasi-2D superconductivity features, including the high anisotropy {\gamma} = 151 and the associated quasi-2D vortices, are also revealed for (Li,Fe)OHFeSe, based on systematic experiments of the electrical transport and magnetization and model fittings. Thus, we establish a new vortex phase diagram for (Li,Fe)OHFeSe, which delineates an emergent quasi-2D vortex-liquid state, and a subsequent vortex-solid dimensional crossover from a pancake-like to a three-dimensional state with decreasing temperature and magnetic field. Furthermore, we find that all the quasi-2D characteristics revealed here for the high-Tc iron selenide superconductor are very similar to those reported for the high-Tc bismuth cuprate superconductors., Comment: 20 pages, 6 figures

Transition metal tellurides (TMTs) have attracted intense interest due to their intriguing physical properties arising from their diverse phase topologies. To date, a wide range of physical properties have been discovered for TMTs, including that they can act as topological insulators, semiconductors, Weyl semimetals, and superconductors. Among the TMT families, MoTe2 is a representative material because of its Janus nature and rich phases. In this Perspective, we first introduce phase structures in monolayer and bulk MoTe2 and then summarize MoTe2 synthesis strategies. We highlight recent advances of Janus MoTe2 in terms of material structures and emerging quantum states. We also provide insight into the opportunities and challenges faced by MoTe2-associated device design and applications. Ministry of Education (MOE) Nanyang Technological University National Research Foundation (NRF) Submitted/Accepted version Z.L. acknowledges support from National Research Foundation Singapore programme NRF-CRP22-2019-0007 and NRFCRP21-2018-0007.This work is also supported by the Ministry of Education, Singapore, under its AcRF Tier 3 Programme “Geometrical Quantum Materials” (MOE2018-T3-1-002). X.Z. acknowledges support from Singapore NTU Presidential Postdoctoral Fellowship (03INS000973C150). G.L. acknowledges support from National Basic Research Program of China from the MOST (2016YFA0300601, 2014CB920904, and 2015CB921402), National Natural Science Foundation of China (92065203, 11527806, and 11874406), Beijing Municipal Science & Technology Commission of China (Z191100007219008), Beijing Academy of Quantum Information Sciences (Y18G08), Strategic Priority Research Program of the Chinese Academy of Sciences (XDB33010300), and by the Synergic Extreme Condition User Facility.

Recently, new states of matter like superconducting or topological quantum states were found in transition metal dichalcogenides (TMDs) and manifested themselves in a series of exotic physical behaviors. Such phenomena have been demonstrated to exist in a series of transition metal tellurides including MoTe2, WTe2, and alloyed MoxW1-xTe2. However, the behaviors in the alloy system have been rarely addressed due to their difficulty in obtaining atomic layers with controlled composition, albeit the alloy offers a great platform to tune the quantum states. Here, we report a facile CVD method to synthesize the MoxW1-xTe2 with controllable thickness and chemical composition ratios. The atomic structure of a monolayer MoxW1-xTe2 alloy was experimentally confirmed by scanning transmission electron microscopy. Importantly, two different transport behaviors including superconducting and Weyl semimetal states were observed in Mo-rich Mo0.8W0.2Te2 and W-rich Mo0.2W0.8Te2 samples, respectively. Our results show that the electrical properties of MoxW1-xTe2 can be tuned by controlling the chemical composition, demonstrating our controllable CVD growth method is an efficient strategy to manipulate the physical properties of TMDCs. Meanwhile, it provides a perspective on further comprehension and sheds light on the design of devices with topological multicomponent TMDC materials.

This paper is concerned with the problem of robust H ∞ static output feedback control for a class of uncertain discrete-time switched systems under mode-dependent persistent dwell-time (MPDT) switching scheme. The interested systems are described by the classical polytopic-type uncertain model with time-varying parametric uncertainties. The purpose of this paper is to design a static output feedback controller that ensures the resulting closed-loop system robustly globally uniformly asymptotically stable (GUAS) with a specified H ∞ performance under MPDT switching. By using a quasi-time-dependent (QTD) and parameter-dependent switched Lyapunov-like function suitable to MPDT switching, the sufficient conditions for stability criterion and H ∞ performance analysis are established. Furthermore, a set of QTD switched static output feedback controllers for the polytopic-type uncertain discrete-time switched system with MPDT are first designed. Finally, the effectiveness and potential of the proposed approaches is demonstrated by a water-quality control system.

Many proposals in exploring topological quantum computation are based on superconducting quantum devices constructed on materials with strong spin-orbit coupling (SOC). For these devices, a full control on both the magnitude and the spatial distribution of the supercurrent would be highly demanded, but has been elusive up to now. We constructed proximity-type Josephson junction on nanoplates of Bi2O2Se, a new emerging semiconductor with strong SOC. Through electrical gating, we show that the supercurrent can be fully turned ON and OFF, and its real-space pathways can be configured either through the bulk or along the edges. Our work demonstrates Bi2O2Se as a promising platform for constructing multifunctional hybrid superconducting devices as well as for searching for topological superconductivity.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have been emerged as a new class of van der Waals materials since the successful isolation of graphene. The strong spin-orbit coupling (SOC) and two-dimensionality give rise to plenty of novel physics including metal-insulator transition, charge density wave (CDW), valleytronics, quantum spin Hall effect, and unconventional superconductivity, which make TMDCs an ideal platform to study the fundamental physics and potential applications. In this review, we firstly introduce the crystal structure of 2D TMDCs materials. Then, we summarize the recent progress in the synthesis, novel physical properties, and applications of 2D TMDCs materials. Finally, a summary and an outlook on the topological superconductivity in this field are presented. 2D TMDCs have a chemical formula of MX2 (M=W, Mo and X=Te, Se, S) with a layered crystal structure. Depending on the coordination environments of M, TMDCs can crystallize in a variety of polytypic structures such as 2 H , 1 T , 1 T ′, and T d phases. In the monolayer 2 H -TMDCs, the breaking of an in-plane mirror symmetry and the presence of the out-of-plane mirror symmetry lead to an Ising spin–orbit coupling (SOC), which serves as an effective out-of-plane field acting on the copper pair and pins the electron spins to out-of-plane directions. This is called Ising superconductivity, which has been observed in gated MoS2, monolayer NbSe2 and TaS2. However, due to the inversion symmetry in monolayer 1 T ′-TMDCs, the introduction of SOC makes them a class of large-gap quantum spin Hall insulators such as monolayer 1 T ′-WTe2. Therefore, if we could consecutively tailor the TMDCs’ structure from 2 H to T d phase, the long-sought topological superconductivity may be realized in one substance by incorporating superconductivity and quantum spin Hall effect together. To explore the extraordinary physics and nanodevice applications, we develop a universal molten-salt-assisted chemical vapor deposition (CVD) method to prepare atomically thin TMDCs, including high-quality 2D superconductors such as monolayer MoTe2 and NbSe2. With the powerful sample growth technique , we demonstrate for the first time that a consecutive structural phase transition from T d to 1 T ′ to 2 H polytype can be realized by increasing the Se concentration in Se-substituted MoTe2. More importantly, the Se-substitution is found to dramatically enhance the superconductivity of the MoTe2 thin film, which is interpreted as the introduction of two-band superconductivity. Furthermore, in bilayer 1 T d-MoTe2, we find that the in-plane upper critical field goes beyond the Pauli paramagnetic limit and shows an emergent two-fold symmetry, which is different from the isotropic in-plane upper critical field in 2 H -TMDCs. We show that this is a result of a new type of asymmetric SOC in 1 T d-TMDCs, which has expanded the well-known Ising SOC. The polytypic structures and strong SOC in 2D TMDCs have led to a variety of novel physics and applications. Recent theoretical works have already shown that 2D TMDCs can be a platform to search for topological superconductivity. With the further development of sample preparation, 2D TMDCs will play an important role in realization of topological quantum computation.

This paper is concerned with the stabilisation problem for a class of discrete-time two-dimensional (2-D) switched systems with persistent dwell-time (PDT). The systems are described by the well-kn...

The unique electronic structure and crystal structure driven by external pressure in transition metal tellurides (TMTs) can host unconventional quantum states. Here, the discovery of pressure‐induced phase transition at ≈2 GPa, and dome‐shaped superconducting phase emerged in van der Waals layered NbIrTe4 is reported. The highest critical temperature (T c) is ≈5.8 K at pressure of ≈16 GPa, where the interlayered Te–Te covalent bonds form simultaneously derived from the synchrotron diffraction data, indicating the hosting structure of superconducting evolved from low‐pressure two‐dimensional (2D) phase to three‐dimensional (3D) structure with pressure higher than 30 GPa. Strikingly, the authors have found an anisotropic transport in the vicinity of the superconducting state, suggesting the emergence of a “stripe”‐like phase. The dome‐shaped superconducting phase and anisotropic transport are possibly due to the spatial modulation of interlayer Josephson coupling ., The correlation of novel electrical properties and structural evolutions in van der Waals layered material is revealed by performing special high‐pressure measurements. A superconducting model is proposed to explain the emergence of “stripe”‐like phases and the evolution of critical temperature. Spatial modulation of interlayer Josephson coupling furthers the understanding of the complex relationships between structure, anisotropy, and superconductivity.

Systematic electrical transport characterizations were performed on high-quality Bi2O2Se nanowires to illustrate its great transport properties and further application potentials in spintronics. Bi2O2Se nanowires synthesized by chemical vapor deposition method presented a high field-effect mobility up to 1.34*104 cm2V-1s-1, and exhibited ballistic transport in the low back-gate voltage (Vg) regime where conductance plateaus were observed. When further increasing the electron density by increasing Vg, we entered the phase coherent regime and weak antilocalization (WAL) was observed. The spin relaxation length extracted from the WAL was found to be gate tunable, ranging from ~100 nm to ~250 nm and reaching a stronger spin-obit coupling (SOC) than the two-dimensional counterpart (flakes). We attribute the strong SOC and the gate tunability to the presence of a surface accumulation layer which induces a strong inversion asymmetry on the surface. Such scenario was supported by the observation of two Shubnikov-de Haas oscillation frequencies that correspond to two types of carriers, one on the surface, and the other in the bulk. The high-quality Bi2O2Se nanowires with a high mobility and a strong SOC can act as a very prospective material in future spintronics., 22 pages, 7 figures

Recently, the transition metal dichalcogenide ${\mathrm{NbTe}}_{2}$ was predicted to be a candidate material of topological semimetal. Here we report the magnetotransport data measured in two devices fabricated from ${\mathrm{NbTe}}_{2}$ nanoflakes. A nonsaturating linear magnetoresistance was observed in both devices at various temperatures. A close analysis shows that the observed linear magnetoresistance is not consistent with the Abrikosov quantum theory; instead, it can be well explained in the framework of the effective-medium theory which describes the classical magnetoresistance of inhomogeneous systems. Our results indicate that the linear magnetoresistance of ${\mathrm{NbTe}}_{2}$ is most likely a classical magnetoresistance induced by disorders and inhomogeneities. This speculation is supported by the abundant domain structures observed in ${\mathrm{NbTe}}_{2}$ crystals in transmission electron microscopy measurements.

Weyl nodes and Fermi arcs in type-II Weyl semimetals (WSMs) have led to lots of exotic transport phenomena. Recently, ${\mathrm{Mo}}_{0.25}{\mathrm{W}}_{0.75}{\mathrm{Te}}_{2}$ has been established as a type-II WSM with Weyl points located near Fermi level, which offers an opportunity to study its intriguing band structure by electrical transport measurements. Here, by selecting a special sample with the thickness gradient across two- (2D) and three-dimensional (3D) regimes, we show strong evidence that ${\mathrm{Mo}}_{0.25}{\mathrm{W}}_{0.75}{\mathrm{Te}}_{2}$ is a type-II Weyl semimetal by observing the following two dimensionality-dependent transport features: (1) a chiral-anomaly-induced anisotropic magnetoconductivity enhancement, proportional to the square of in-plane magnetic field (${B}_{\mathrm{in}}^{2}$); and (2) an additional quantum oscillation with thickness-dependent phase shift. Our theoretical calculations show that the observed quantum oscillation originates from a Weyl-orbit-like scenario due to the unique band structure of ${\mathrm{Mo}}_{0.25}{\mathrm{W}}_{0.75}{\mathrm{Te}}_{2}$. The in situ dimensionality-tuned transport experiment offers an alternative strategy to search for type-II WSMs.

Transition metal tellurides (TMTs) have attracted intense interest due to their intriguing physical properties arising from their diverse phase topologies. To date, a wide range of physical properties have been discovered for TMTs, including that they can act as topological insulators, semiconductors, Weyl semimetals, and superconductors. Among the TMT families, MoTe

Recently, a Corbino-geometry type of Josephson junction constructed on the surface of topological insulators has been proposed for hosting and braiding Majorana zero modes. As a first step to test this proposal, we successfully fabricated Corbino-geometry Josephson junctions (JJs) on the surface of Bi2Te3 flakes. Ac Josephson effect with fractional Shapiro steps was observed in the Corbino-geometry JJs while the flux in the junction area was quantized. By analyzing the experimental data using the resistively shunted Josephson junction model, we found that the Corbino-geometry JJs exhibit a skewed current–phase relation due to its high transparency. The results suggest that Corbino-geometry JJs constructed on the surface of topological insulators may provide a promising platform for studying Majorana-related physics.

Recently, new states of matter like superconducting or topological quantum states were found in transition metal dichalcogenides (TMDs) and manifested themselves in a series of exotic physical behaviors. Such phenomena have been demonstrated to exist in a series of transition metal tellurides including MoTe

Precision equipment is usually accompanied with vibrations during road or railway transportation. Sometimes the vibration exceeds the given limit, leading to the damage of the equipment. It is necessary to control the vibration during the transportation. However, it is still difficult to adjust the parameters of a designed vibration isolation system for the transportation of different precision equipment under various road conditions. Aiming at satisfying the vibration isolation requirements of different precision equipment, this paper proposes a parallel air spring vibration isolation system based on the principle of limiting lateral deflection. According to the measured parameters, a rigid-body dynamics simulation model of parallel air spring vibration isolation system is established. Then its feasibility is verified, and the optimal parameters of the vibration isolation system are obtained by a simulation. Finally, the vibration isolation system is built and installed in the equipment to carry out the real vehicle transportation test. The test results show that the transportation vibration isolation system based on the parallel air spring structure has not only excellent vibration isolation efficiency but also acceptable lateral stability. The research results in this paper can provide a reference for the design of the vibration isolation system for the large precision equipment transportation.

The precision equipment bears the vibration excited by the road roughness during transportation, and faces the risk of damage arising from the vibration. The parallel air spring vibration isolation system (PAVS) has an excellent vibration isolation performance, so has a good application prospect in the precision equipment transportation. But under the conditions of abnormal road and eccentric load, PAVS bears great vibration excitation, and the resulting large deformation of air spring makes the air spring stiffness nonlinear, so to obtain an excellent vibration isolation performance faces a great challenge. Aiming at this problem, based on the measured parameters, the nonlinear dynamics model of PAVS is proposed. Then, the influence of air spring under large deformation on the vibration isolation characteristics is discussed. Finally, under the condition of eccentricity of precision equipment, the vibration isolation characteristics of PAVS with equal height control strategy is investigated. The results show that PAVS with the equal height control strategy has good vibration isolation characteristics. So for the transportation of large precision equipment, PAVS is a potentially useful method.

We studied anomalous Josephson effect (AJE) in Josephson trijunctions fabricated on Bi$_2$Se$_3$, and found that the AJE in T-shaped trijunctions significantly alters the Majorana phase diagram of the trijunctions, when an in-plane magnetic field is applied parallel to two of the three single junctions. Such a phenomenon in topological insulator-based Josephson trijunction provides unambiguous evidence for the existence of AJE in the system, and might provide an additional knob for controlling the Majorana bound states in the Fu-Kane scheme of topological quantum computation., Comment: 6 pages, 3 figures

Andreev bound states (ABSs), as a close resemblance and a prototype of Majorana bound states, attracted particular interest in semiconductor-superconductor hybrids. So far, ABSs were explored as an equilibrium behavior employing tunneling spectroscopy. Under nonequilibrium, theorists did predict that the local density of states (DOS) of the ABSs split and broaden. We investigated an InAsSb quantum dot coupled to two superconductors to explore the nonequilibrium dynamics of ABSs and their interplay with Kondo effect. Through tunneling spectroscopy, we demonstrated a full picture of the nonequilibrium dynamic splitting and broadening of ABSs, which interplays with the nonequilibrium Kondo DOS. Since the observed features might mimic those in the normal superconductor-topological superconductor or Majorana junctions, our discovery could provide a relevant comparison to benchmark the Majorana signal in future experiments.

In this paper, the static output feedback control for discrete-time two-dimensional switched systems with mode-dependent persistent dwell-time is studied. The discrete-time two-dimensional switched system is formulated by the famous Fornasini–Marchesini local state-space model. Based on a suitable Lyapunov function for mode-dependent persistent dwell-time, a quasi-time-dependent static output feedback controller which guarantee the resulting closed-loop system exponentially stable is presented. The theoretical result is verified by a numerical example.

We report on the successful synthesis and low-temperature electron transport investigations of a new form of material---$\mathrm{B}{\mathrm{i}}_{2}{\mathrm{O}}_{2}\mathrm{Se}$ semiconducting nanowires. Gate-tunable 0- and $\ensuremath{\pi}\text{\ensuremath{-}}h/e\phantom{\rule{4pt}{0ex}}(h$ is the Planck constant and $e$ the elementary charge) periodic resistance oscillations in longitudinal magnetic field were observed unexpectedly, demonstrating novel quasiballistic, phase-coherent surface states in $\mathrm{B}{\mathrm{i}}_{2}{\mathrm{O}}_{2}\mathrm{Se}$ nanowires. By reaching a very good agreement between the calculated density of states and the experimental data, we clarified the mechanism to be the one-dimensional subbands formed along the circumference of the nanowire rather than the usually considered Aharonov-Bohm interference. A qualitative physical picture based on downward band bending associated with the complex band structure is proposed to describe the formation of the surface states.

We carried out a phase-sensitive experiment on Josephson trijunctions constructed on the surface of three-dimensional topological insulator ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$. Through local flux contol and contact resistance measurement, we observed that the minigap at the ends of the trijunctions approaches zero linearly with varying phase difference and closes completely at $\ensuremath{\pi}$ phase difference. The minigap at the center of the trijunction is protected to close over extended regions in phase space. These results agree with the theory by Fu and Kane [Phys. Rev. Lett. 100, 096407 (2008)].

A series of experimental and theoretical studies have demonstrated that Bi1-xNdxFeO3 ceramics with morphotropic phase boundaries (MPBs) exhibit a very complex phase-transition process including the displacive ferroelectric phase transition and reorientation of antiferromagnetic alignments [Chem. Mater. 23, 2166 (2011); Adv. Funct. Mater. 25, 552 (2015)]. In this work, such complex phase-transition process in the Bi0.85Nd0.15FeO3 ceramic is detected by electric and magnetic responses as the function of frequency. First, the phase transition from orthorhombic Pbam phase (O2) to orthorhombic Pbnm phase (O1) is found to be accompanied by the change in the local strain induced by MPBs. Second, the electric response at O2→O1 transition with the disappearance of antiferroelectric order showed the relaxation and reversible rotation of the ferroelectric order coupled with the local strain. The moderate active energy of such coupling (∼2.7 eV) facilitates the possibility of recovering the deformation of Bi1-xNdxFeO3 ceramic by an external electric field. Third, the weak magnetic response is frequency-independent, and the reorientation of the antiferromagnetic order is also reversible. Finally, the rotation of ferroelectric/magnetic order connected to MPBs in the ceramic is discussed.

Consecutively tailoring few-layer transition metal dichalcogenides MX

The impact of the bottleneck is obvious duringthe peak period because of the limited capacity and the strong cluster effect of subway passenger. The bottleneck facility can affect the overall operational efficiency of the station and decrease the comfort of passengers. The objective of this paper is to improve the efficiency of the whole network in the station by analyzing the passengers queuing characteristics of different facilities and to adjusting the high-density passenger flow. The performance of finite queuing network in the subway station is well evaluated based on N/G/C/C state-dependent space model and M/M/C/C model. The queuing model is well employed to analyze the procedure of passenger movement, calculate the key parameters at certain area and identify the bottleneck. The method of multipoint interlink control method is applied to optimize passenger flow distribution at bottlenecks. According to the facility layout and passenger flow characteristics of the typical streamline network, an optimal scheme for the mitigation was designed. Case study of the subway stations in Beijing were implemented to verify the validity and practicability of the proposed method.

We report single crystal growth of CoSi, which has recently been recognized as a new type of topological semimetal hosting fourfold and sixfold degenerate nodes. The Shubnikov-de Haas quantum oscillation (QO) is observed on our crystals. There are two frequencies originating from almost isotropic bulk electron Fermi surfaces, in accordance with band structure calculations. The effective mass, scattering rate, and QO phase difference of the two frequencies are extracted and discussed., To appear on Chinese Physics Letters

We report the discovery of superconductivity in high-quality single crystals of transition-metal pnictides WP grown by chemical vapor transport method. Bulk superconductivity is observed at ${T}_{\text{c}}\ensuremath{\sim}0.8\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ at ambient pressure by electrical resistivity, ac magnetic susceptibility, and specific-heat measurements. The effects of magnetic field on the superconducting transitions are studied, leading to a large anisotropy parameter around 2 with the in-plane and out-of-plane upper critical fields of ${\ensuremath{\mu}}_{0}{H}_{\text{c}2,\ensuremath{\parallel}}=17.2\phantom{\rule{0.28em}{0ex}}\mathrm{mT}$ and ${\ensuremath{\mu}}_{0}{H}_{\text{c}2,\ensuremath{\perp}}=8.5\phantom{\rule{0.28em}{0ex}}\mathrm{mT}$, respectively. The low value of electron-phonon coupling estimated from the normal-state resistivity and specific-heat measurements suggest that WP is a weak-coupling BCS superconductor. Our finding demonstrates that WP is the first superconductor among $5d$--transition metal pnictides with MnP-type structure at ambient pressure, which will help in the search for new superconductors in transition-metal pnictides.