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Blockchain is a decentralized, shared ledger that aggregates blocks of data in a factual data structure in chronological order using a chain structure. Two hundred sixty thousand tokens, or 98% of the around 2.5 million smart contracts in Ethereum network, are ERC-20 tokens. The ERC20 standard specifies constructors for token contracts that establish and initialize the contract state. The Ethereum wallet and Ethereum decentralized, centralized applications can access tokens through these standard interfaces. Security vulnerabilities in ERC-20 have drawn a lot of attention lately in recent years. This paper summarizes some basic security vulnerabilities and suggests avoiding multiple withdrawal attacks. Tokens can be used to support dApps, access blockchain services, trade, and obtain voting rights. Various tokens exist depending on their properties and use cases, including governance, utility, security, transaction, and platform tokens. Tokens can be sorted as fungible tokens and non-fungible tokens. Tokens that can be fungible are identical, divisible, and can be instead of money. Non-fungible tokens have a single owner and are unique.

The demand for high-performance semiconductors in electronics and optoelectronics has prompted the expansion of low-dimensional materials research to ternary compounds. However, photodetectors based on 2D ternary materials usually suffer from large dark currents and slow response, which means increased power consumption and reduced performance. Here we report a systematic study of the optoelectronic properties of well-characterized rhombohedral ZnIn2S4 (R-ZIS) nanosheets which exhibit an extremely low dark current (7 pA at 5 V bias). The superior performance represented by a series of parameters surpasses most 2D counterparts. The ultrahigh specific detectivity (1.8 x 10^14 Jones), comparably short response time ({\tau}_rise = 222 {\mu}s, {\tau}_decay = 158 {\mu}s) and compatibility with high-frequency operation (1000 Hz) are particularly prominent. Moreover, a gate-tunable characteristic is observed, which is attributed to photogating and improves the photoresponse by two orders of magnitude. Gating technique can effectively modulate the photocurrent-generation mechanism from photoconductive effect to dominant photogating. The combination of ultrahigh sensitivity, ultrafast response and high gate tunability makes the R-ZIS phototransistor an ideal device for low-energy-consumption and high-frequency optoelectronic applications, which is further demonstrated by its excellent performance in optical neural networks and promising potential in optical deep learning and computing., Comment: 33 pages, 8 figures, TOC, Supporting Information

Two-dimensional (2D) elementary tellurium (Te) has attracted intensive attention due to its potential applications in short-wave infrared photodetector devices. Here, we report hydrothermally synthesized 2D Te nanoflakes for short-wave infrared photodetectors with high performance. A Te-based photodetector exhibits a peak responsivity of 51.85 A W

We report a highly efficient and easily transferable poly(vinyl alcohol) (PVA)-assisted exfoliation method, which allows one to obtain van der Waals materials on large scales, e.g., centimeter-scale graphite flakes and hundred-micrometer-scale several layers of ZnIn

The influences of Mn substitution at the Ir site of Sr

The discovery of magnetism in van der Waal (vdW) materials has aroused substantial interest in the exploration of magnetic interactions toward a two-dimensional (2D) limit. Here, we report the engineering of magnetic properties in MnPS3(1-x)Se3x compounds by substituting the non-magnetic chalcogenide S atoms with Se atoms. The anisotropic antiferromagnetic transition of MnPS3(1-x)Se3x compounds is gradually modulated by controlling the Se concentration, including the monotonic decrease in the Néel temperature and Curie–Weiss temperature with increasing Se concentration, and the Se concentration dependence of a spin-flop process. In addition, the magnetic phase diagram is established, in which an exotic mixed antiferromagnetic state appears due to the competition between the magnetic orderings in parent materials of MnPS3 and MnPSe3. Our findings validate the possibility of the manipulation of magnetic properties in magnetic vdW materials through the substitution of chalcogenide ions and pave the way toward the engineering of magnetic interactions and the designing of magnetic devices in two-dimensional magnetic vdW materials.

Using dynamic cantilever magnetometry (DCM), the magnetic phases in H -out-of-plane and H -in-plane configurations of a FeGe slab were investigated. We recorded magnetic field-dependent frequency shifts with static temperature (f -H measurements) and temperature-dependent frequency shifts with static magnetic field (f- T measurements). Based on these data, we constructed the H – T phase diagrams in both configurations. Skyrmion phase (SkX) can be recognized in H -out-of-plane configuration. While no signature of SkX can be recognized in H -in-plane configuration. Meanwhile, the critical magnetic field for the transition from conical phase to field-polarized phase in H -out-of-plane configuration is higher than in H -in-plane configuration. We attribute these two differences to signal-to-noise ratio and demagnetizing field in two configurations, respectively. This work demonstrated the ability of DCM to probe magnetizations of thick or tilted magnetic films, which are difficult to measure using Lorentz transmission electron microscopy or vibrating sample microscopy.

The transport and thermoelectric properties of the LaO 1 − x F x BiPbS 3 compounds are studied. On the transport part, fluorine doping effectively reduces the electrical resistivity, and transforms the transport behavior from semiconducting-like to metallic-like. An evident enhancement of thermoelectric performance (power factor) is achieved in LaO 0.6 F 0.4 BiPbS 3 , with an obviously larger absolute value of Seebeck coefficient ( | S | ) compared to the parent compound. Hall coefficient measurements reveal the depression of effective carrier density for all the doped samples at high temperatures. The present results suggest that electron carriers alone can not explain the improvement of thermoelectric properties by fluorine doping, the conduction of ionic carriers should be taken into account.

We conducted a study of critical exponents to investigate the nature of paramagnetic to ferromagnetic phase transition in a La $$_{\mathrm{0.67}}$$ Ba $$_{\mathrm{0.33}}$$ MnO $$_{\mathrm{3}}$$ (LBMO) film deposited on SrTiO $$_{\mathrm{3}}$$ . To this end, we performed dc magnetization M (H, T) measurements around the Curie temperature ( $$T_{\mathrm{C}}\sim $$ 276.5 K) within a temperature range that includes the critical region $$|\varepsilon |$$ $$=$$ $$|T-T_{\mathrm{C}}|$$ / $$T_{\mathrm{C}} < 0.05$$ . We found that the transition is a second-order transition. Three main critical exponents, namely $$\beta $$ (0.387), $$\gamma $$ (1.309) and $$\delta $$ (4.634), and the critical temperature $$T_{\mathrm{C}} =$$ 276.6 K are derived from the modified Arrott plots. These exponents obey the Widom relation $$\delta =$$ 1 $$+\gamma $$ / $$\beta $$ and are able to collapse a bunch of isothermal magnetization data into two branches below and above $$T_{\mathrm{C}}$$ based on the single scaling equation M( $${H, \varepsilon }$$ ) $$\varepsilon ^{-\beta } = {f}_{\pm }({H} \varepsilon ^{({-\beta +\gamma })})$$ . The critical behavior in LBMO film is close to a 3D Heisenberg model, although certain long-range interactions still exist. Compared to a polycrystalline bulk sample, the long-range interactions are greatly suppressed, which may be attributed to the reduced dimensionality.

The ability that one system immediately affects another one by using local measurements is regarded as quantum steering, which can be detected by various steering criteria. Recently, Mondal et al. [Phys. Rev. A 98, 052330 (2018)] derived the complementarity relations of coherence steering criteria, and revealed that the quantum steering of a system can be observed through the average coherence of a subsystem. Here, we experimentally verify the complementarity relations between quantum steering criteria by employing two-photon Bell-like states and three Pauli operators. The results demonstrate that if prepared quantum states can violate two setting coherence steering criteria and turn out to be steerable states, then they cannot violate the complementary settings criteria. Three measurement settings inequalities, which establish a set of complementarity relations between these two coherence steering criteria, are always obeyed by all prepared quantum states in experiment. In addition, we experimentally certify that the strengths of coherence steering criteria depend on the choice of coherence measure. In comparison with two setting coherence steering criteria based on ${l}_{1}$ norm of coherence and relative entropy of coherence, our experimental results show that the steering criterion based on skew information of coherence is the strongest in detecting the steerability of two-photon Bell-like states. Thus, our experimental demonstration can deepen the understanding of the relation between the quantum steering and quantum coherence.

Tricritical phenomenon appearing in multiple phases is a fundamental and attractive issue in condensed-matter physics. Monopnictide DySb, a candidate for potential magnetic topological semimetal with an antiferromagnetic ground state, has been found to possess complex and intriguing field-induced magnetic phase transitions. In this work, critical behaviors of single-crystal DySb are investigated systematically, which generate a series of critical exponents including $\ensuremath{\beta}=0.244(2)$, $\ensuremath{\gamma}=0.827(2)$, and $\ensuremath{\delta}=4.425(1)$ for $H\ensuremath{\parallel}[001]$. The deduced critical exponents verified by Widom law and scaling equations are close to a tricritical mean-field model, suggesting a field-induced tricritical phenomenon in DySb. Based on the universality principle, a detailed $H\text{\ensuremath{-}}T$ phase diagram around the phase transition is constructed for $H\ensuremath{\parallel}[001]$, in which a tricritical point is revealed at temperature and field of (7.5 K, 51.4 kOe) on intersected boundaries of antiferromagnetic, forced ferromagnetic, and paramagnetic phases. Moreover, a triple point is found at the intersection (9.2 K, 19.7 kOe) of paramagnetic and two kinds of antiferromagnetic states. Such a fascinating phase diagram is indicative of delicate competition and balance between multiple magnetic interactions in this system, and lays a solid foundation for future research in topological transition and criticality.

Pezzini et al. reported an unconventional mass enhancement in topological nodal line semimetal ZrSiS (Nat. Phys. 14, 178 (2018), whose origin remains puzzling. In this material, strong short-range interactions might induce excitonic particle-hole pairs. Here we study the renormalization of fermion velocities and find that the mass enhancement in ZrSiS can be well understood if we suppose that ZrSiS is close to the quantum critical point between semimetal and excitonic insulator. Near this quantum critical point, the fermion velocities are considerably reduced by excitonic quantum fluctuation, leading to fermion mass enhancement. The quasiparticle residue is suppressed as the energy decreases but is finite at zero energy. This indicates that ZrSiS is a strongly correlated Fermi liquid, and explains why the mass enhancement is weaker than non-Fermi liquids. Our results suggest that ZrSiS is a rare example of 3D topological semimetal exhibiting unusual quantum criticality., Comment: 6+11 pages, 4+1 figures, 1 table

The Einstein-Podolsky-Rosen (EPR) steering is an intermediate quantum nonlocality between entanglement and Bell nonlocality, which plays an important role in quantum information processing tasks. In the past few years, the investigations concerning the EPR steering have been demonstrated in a series of experiments. However, these studies rely on the relevant steering inequalities and the choices of measurement settings. Here, we experimentally verify the EPR steering via entanglement detection without using any steering inequality and measurement setting. By constructing two new states from a two-qubit state, we observe the EPR steering by detecting the entanglement of these new states. The results show that the entanglement of the newly constructed states can be regarded as an unusual kind of steering witness for these states. Compared to the results of Xiao et al. [Phys. Rev. Lett. 118, 140404 (2017)], we find that the ability to detect the EPR steering in our scenario is stronger than that of two-setting projective measurements, which can observe more steerable states. Hence, our demonstrations can deepen the understanding of the connection between the EPR steering and entanglement.

It is commonly anticipated that an insulating state will collapse in favor of an emergent metallic state at high pressures: The average electron density must increase with pressure, while the electronic bandwidth is expected to broaden and fill the insulating energy band gap. Here we report an unusually stable insulating state that persists up to at least 185 GPa in $\mathrm{S}{\mathrm{r}}_{2}\mathrm{Ir}{\mathrm{O}}_{4}$, the archetypical spin-orbit-driven ${J}_{\mathrm{eff}\phantom{\rule{0.28em}{0ex}}}=1/2$ insulator. This study shows that the electrical resistance R of single-crystal $\mathrm{S}{\mathrm{r}}_{2}\mathrm{Ir}{\mathrm{O}}_{4}$ initially decreases with applied pressure P, reaches a minimum in the range 32--38 GPa, then abruptly rises to recover the insulating state with increasing P up to 185 GPa. However, evidence of a saturation of R below 80 K for $P\ensuremath{\ge}124\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$ GPa raises the possibility of a low-temperature exotic state. Our synchrotron x-ray diffraction and Raman scattering data show the emergence of the rapid increase in R is accompanied by a structural phase transition from the native tetragonal $I{4}_{1}/acd$ phase to an orthorhombic $Pbca$ phase (with much reduced symmetry) at 40.6 GPa. The clear correspondence of the onset pressures of these two anomalies is key to understanding the stability of the insulating state at megabar pressures: Pressure-induced, structural distortions prevent the expected onset of metallization, despite the sizable volume compression attained at the highest pressure accessed in this study.

The 5d transition metal oxide Sr2IrO4 has attracted much interest in the high-temperature superconductivity community since it highly resembles the cuprate superconductor in crystal and electronic structures. Here, we report on the transport and magnetic properties of Zn-doped Sr2IrO4. It is found that the energy gap of Sr2IrO4 is rapidly decreased with a small amount of Zn doping. Consequently, the electrical conductivity is significantly enhanced. The present work could serve as the prerequisite stage in exploring the possible superconductivity of the Sr2IrO4 compound.

The present paper investigates the magnetic and magnetoelectric properties of Bi2Ir2−xMnxO7 compounds with respect to the degree of Mn doping denoted by x. It is found that the antiferromagnetic (AFM) interactions are initially enhanced with increasing x, but are then weakened with further increases in x. These findings are explained on the basis of the competition among AFM Ir–Ir, AFM Ir–Mn, and ferromagnetic Mn–Mn interactions. In addition, the electric transport properties at the temperature range studied present a metal-insulator transition in the range 0.05 ≤ x ≤ 0.15, while an insulating state occurs for x > 0.15 because of electron localization. At low temperatures, a small positive magnetoresistance (MR) effect is observed for x = 0, whereas a negative MR effect is observed for all Mn-doped samples. The 3d–5d electron interactions play a dominant role in determining the magnetic properties of the doped samples.

Influence of short-range four-fermion interactions on quadratic and cubic nodal line fermion systems is studied by renormalization group theory. It is found that arbitrarily weak four-fermion interaction could drive quadratic or cubic nodal line fermion system to a new phase. According to the initial conditions and value of fermion flavor, the system may appear three kinds of instabilities. First, quadratic or cubic nodal line is split into conventional nodal lines, thus the system becomes nodal line semimetal. Second, finite excitonic gap is generated, and the system becomes an excitonic insulator. Third, the system is driven into superconducting phase. Thus, quadratic and cubic nodal line fermion systems are rare strong correlated fermion systems in three dimension under the influence of four-fermion interactions. These theoretical results may be verified in the candidates for quadratic and cubic nodal line fermion systems., 19 pages, 10 figures

Experimental and theoretical studies are performed on ${\mathrm{La}}_{3}{\mathrm{Ir}}_{3}{\mathrm{O}}_{11}$, an iridate hosting a $+4.33$ fractional valence state for Ir ions and a three-dimensional frustrated structure composed of edge-shared ${\mathrm{Ir}}_{2}{\mathrm{O}}_{10}$ dimers. These features are expected to enhance intersite hoppings and reduce magnetic moments of Ir ions. However, a spin-orbit driven Mott insulating transport is observed, which is supported by our first-principles calculations. Most importantly, geometrical frustration and competing interactions result in a non-Curie-Weiss paramagnetic ground state, revealing no magnetic order down to 2 K. This unusual state is further demonstrated by a theoretical modeling process, suggesting a possible candidate for the spin-liquid state.

Critical behaviors of Fe1.5−xCoxRh0.5Mo3N ( x = 0.5 , 1.0 , 1.2 ) are investigated, which are well known as a new family hosting skyrmion phase. The critical exponents β, γ, and δ, which correspond to the magnetization, are obtained by the modified Arrott plot and critical isothermal analysis. The reliability of these critical exponents are testified by the Widom scaling law and scaling equation. The critical exponents of Fe1.5−xCoxRh0.5Mo3N ( x = 0.5 , 1.0 , 1.2 ) are close to the universality class of 3D-Heisenberg model, which suggests that the magnetic coupling in this system is of an isotropic short-range type.

As a result of the 3-D magnetic field and complex structure, existing motor design programs are not suitable for the transverse flux permanent magnet motor (TFPMM). Hence, a method combining particle swarm optimization (PSO) algorithm and response surface methodology (RSM) is proposed to optimize a TFPMM. The optimization aims to maximize the no-load electromotive force (EMF) to get higher torque density in the same volume of the motor. First, central composite design method is adopted for experiments on geometrical design variables. Next, the finite-element method is utilized for simulations to determine the coefficients of the second-order analytical model for the RSM. The optimal solution of the model is then obtained by MATLAB PSO toolbox. Finally, we compare the optimized model with a prototype owning the same volume. The results show that with optimization, the no-load back EMF is improved by 10%, so is the output torque, which illustrates the effectiveness of the optimization method.

Quantum entanglement, quantum steering and Bell nonlocality, as significant quantum resources in the field of quantum information science, can achieve variously valuable quantum information tasks. Among of them, quantum entanglement and Bell nonlocality are the weakest and strongest nonlocal correlations, respectively. One can capture the quantum steering and Bell nonlocality via violating steering inequality and Bell inequality, respectively. In general, the detections of quantum steering and Bell nonlocality are strictly harder than entanglement detection. Here, based on steering inequality test and quantum state tomography, we attain various nonlocal correlations and experimentally demonstrate that the estimations of quantum steering and Bell nonlocality can be realized according to the quantum entanglement of the prepared two-photon test states. The estimated efficiency of quantum steering is stronger than the one of Bell nonlocality in this scenario, i.e., more steerable two-photon test states can be verified through quantum entanglement. In addition, quantum steering and Bell nonlocality are bounded by the corresponding upper and lower bounds, and these bounds cannot be punctured by all prepared two-photon states in experiment. These results are conducive to understand the relations among these nonlocal correlations.

Two-dimensional (2D) materials attached with flexible substrates enable possibilities to apply their superior properties to the rapidly increasing demand for foldable displays and wearable biosensors in the internet-of-things technology. However, previous two-step strategy to construct the flexible devices, namely first obtaining 2D materials elsewhere and then transferring them onto flexible substrates, can cause huge problems, including irreversibly undermining the device performance and limiting the material size. Here we propose a new one-step strategy (other than the liquid phase processing and low temperature synthesis methods), namely directly depositing appropriate 2D materials onto flexible substrates, which involves no transferring and can maintain the crystal quality and properties to the greatest extent. More importantly, this strategy in principle has no limit in the film size, hence removing a main obstacle for the practical use of flexible films, such as complex logic operations and large-area optoelectronic applications. Using this strategy, a centimeter-scale SnSe2film is directly grown on polydimethylsiloxane, which is characterized as a uniform, out-of-plane oriented and semiconducting film that is robust to deformations. Based on the film, a flexible photodetector is fabricated and distinct photoresponse to a broad spectrum of light (405 - 830 nm) is observed, with remarkable technical parameters.

Superconducting proximity effect in the heterostructures opens up access to engineer superconductivity at the interface, and has inspired substantial research interest in the past decade. Here, we fabricate the van der Waals 2H-TaS2/NbSe2 heterostructure through the mechanical exfoliation and dry transfer technique. Enhanced superconductivity in 2H-TaS2 flakes with increased superconducting transition temperature by about 0.8 K is observed. Such enhancement is believed to be related to the leakage of the Cooper pairs from NbSe2 flakes to 2H-TaS2 flakes. In addition, the critical current of the superconducting transition of NbSe2 flakes is also increased in the heterostructures, which is related to the strengthened pairing strength of Cooper pairs in NbSe2 flakes arising from the interfacial coupling between NbSe2 flakes and 2H-TaS2 flakes. Our findings will open perspectives for insight into the superconducting proximity effect in the van der Waals heterostructures.

The continuing demand for new optoelectronic devices drives researchers to seek new materials suitable for photodetector applications. Recently, ternary compound semiconductors have entered researchers’ field of vision, among which chalcohalides have attracted special interest because of their rich properties and unique crystal structure consisting of atom chains and inter-chain van der Waals gaps. We have synthesized high-quality BiSeI single crystals with [110]-plane orientation and fabricated a photodetector. The optoelectronic measurements show a pronounced photocurrent signal with outstanding technical parameters, namely high responsivity (3.2 A/W), specific detectivity (7 × 1010 Jones) and external quantum efficiency (622%) for λ = 635 nm, V ds = 0.1 V and P opt = 0.23 mW/cm2. The high performance of BiSeI photodetector and its layer structure make it a promising candidate for low-dimensional optoelectronic applications.

Atomically thin two-dimensional (2D) materials are the building bricks for next-generation electronics and optoelectronics, which demand plentiful functional properties in mechanics, transport, magnetism and photoresponse. For electronic devices, not only metals and high-performance semiconductors but also insulators and dielectric materials are highly desirable. Layered structures composed of 2D materials of different properties can be delicately designed as various useful heterojunction or homojunction devices, in which the designs on the same material (namely homojunction) are of special interest because preparation techniques can be greatly simplified and atomically seamless interfaces can be achieved. We demonstrate that the insulating pristine ZnPS3, a ternary transition-metal phosphorus trichalcogenide, can be transformed into a highly conductive metal and an n-type semiconductor by intercalating Co and Cu atoms, respectively. The field-effect-transistor (FET) devices are prepared via an ultraviolet exposure lithography technique. The Co-ZnPS3 device exhibits an electrical conductivity of 8 × 104 S/m, which is comparable to the conductivity of graphene. The Cu-ZnPS3 FET reveals a current ON/OFF ratio of 105 and a mobility of 3 × 10−2 cm2⋅V−1⋅s−1. The realization of an insulator, a typical semiconductor and a metallic state in the same 2D material provides an opportunity to fabricate n-metal homojunctions and other in-plane electronic functional devices.

The magnetic entropy change [Δ S M ( T , H )] around the phase transition temperature T C is investigated by the scaling method for Fe 0.5 Co 0.5 Si, which exhibits a Skyrmion phase below T C . The parameters of Δ S M ( T , H ) exhibit field dependent behaviors. The Δ S M ( T , H ) curves under high field can be well scaled into a single universal curve independent of external field and temperature. However, Δ S M ( T , H ) curves under low field become divergent just below T C , which indicates a characteristic of first-order transition. The scaling investigation of Δ S M ( T , H ) curves indicates that the phase transition in Fe 0.5 Co 0.5 Si is of a weak first-order type in low field region, while it is driven into a second-order one under high field. This weak first-order phase transition in low field region resembles that in typical skyrmion system MnSi which is caused by the critical fluctuation. The result suggests that critical fluctuation plays an important role in the phase transition and formation of skyrmion state.

We perform a systematic investigation on the effects of Ba and La doping on the lattice and transport properties of Sr2IrO4, which is theoretically predicted to be a host compound of high-temperature superconductivity. We observe a drastic straightening of the Ir–O–Ir bond angle in the Ba-doped samples. The straightening of the bond angle is much weaker in the La-doped samples. It is found that the La doping leads to the introduction of electron-type charge carriers, while the charge carrier concentration does not change too much in the Ba-doped samples. As a result, both the resistivity and the magnetic moments decrease much faster in the La-doped samples, compared to those in the Ba-doped samples. The present results suggest that it is the charge carrier density rather than the Ir–O–Ir bond angle that dominates the magnetic and transport properties of the Sr2IrO4 system.

SmPO4 coated Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials were prepared by the precipitation method and calcined at 450 °C. The crystal structures and electrochemical properties of the pristine and coated samples are studied by X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, electron diffraction spectroscopy, galvanostatic cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). It has been found that the electrochemical performances of the Li-rich cathode material have been substantially improved by SmPO4 surface coating. Especially, the 2 wt% SmPO4-coated sample demonstrates the best cycling performance, with capacity retention of 88.4% at 1 C rate after 100 cycles, which is much better than that of 72.3% in the pristine sample. The improved electrochemical properties have been ascribed to the SmPO4 coating layer, which not only stabilizes the cathode structure by decreasing the loss of oxygen, but also protects the Li-rich cathode material from side reaction with the electrolyte and increases the Li+ migration rate at the cathode interface.

Critical phenomenon of the noncentrosymmetric Cr11Ge19, which exhibits an itinerant ferromagnetic ground state, is investigated by scaling of the magnetic entropy change [ΔSM(T,H)]. It is found that parameters δFWHM (the full width at half maximum), − Δ S M m a x (the maximum of the magnetic entropy change), and RCP (the relative cooling power) of ΔSM(T) are governed by the power law of critical exponents. With the critical exponents, ΔSM(T,H) curves are scaled into a universal curve independent of temperature and field, which suggests that the magnetic transition is of a second order type. The universal collapse of ΔSM(T,H) indicates that the critical behavior of Cr11Ge19 can be well described by the scaling laws for the critical phenomenon. Moreover, the ΔSM follows the power law of Hn with n(T,H)=dln|ΔSM|/dln(H). The temperature dependence of n values reach minimum at ∼ 71.5 K. Based on the magnetic specific change ΔCp(T,H), the actual magnetic transition temperature is strictly determined as TC=71.3±0.2 K for the single crystal Cr11Ge19.

The iso-spinel structural systems CuIr2S4 and MgTi2O4 exhibit phase transitions of a similar nature at ∼230 K and ∼260 K respectively, which are explained as an orbitally-induced Peierls phase transition. However, in this work, we uncover that the applied pressure has opposite pressure effects on the phase transitions in CuIr2S4 and MgTi2O4. As the pressure increases, the phase transition temperature (TMI) for CuIr2S4 increases while that for MgTi2O4 decreases. In addition, the phase transition intensity becomes weaker for CuIr2S4 but gets stronger for MgTi2O4 under pressure. Our results indicate that the applied pressure suppresses the metallic phase in CuIr2S4, while enhances that in MgTi2O4. Combining the experimental observations with first-principles electronic structure calculations, we suggest that the opposite pressure effects in CuIr2S4 and MgTi2O4 originate from the different orbital ordering configurations (dxy, dyz/dxz) caused by different lattice distortions in these two systems. Our findings indicate directly that the interplay between the orbital and lattice degrees of freedom plays an important role in the orbitally-induced Peierls phase transition.

The transport property of chalcogenide spinel CuCr 2 Se 4 with an itinerant ferromagnetic ground state can be modulated by doping of bromine, where the half-metallic state can be realized around x = 0.25 in CuCr 2 Se 4− x Br x system. In this work, the single crystal CuCr 2 Se 4− x Br x ( x = 0.25) with the cleave surface (111) plane has been investigated by the electron paramagnetic resonance (EPR) spectroscopy. The EPR results show that the in-plane magnetization is strong while the out-of-plane one is weak, which indicate that the spins are ferromagnetic ordered within the (111) plane. In addition, the isothermal EPR spectra in the ferromagnetic phase display that the spin coupling strength ( λ ) and crystal field (Δ CF ) depend on the rotation angle φ as relation λ /Δ CF ∝ cos φ . Moreover, the peak-to-peak linewidth Δ H PP increases linearly with the decrease of temperature, which suggests that the spin-orbit coupling is enhanced linearly with temperature cooling.

All two-qubit states can be characterized visually by a quantum steering ellipsoid (QSE) inside the Bloch sphere, and their quantum resources (such as entanglement and discord) can be directly reflected via the geometric properties of QSE. In this work, we obtain QSE of bipartite Werner state interacting with a reservoir and probe the effects of the strong coupling regime and weak coupling regime on the maximal steered coherence (MSC) and concurrence in QSE framework. It is concluded that the MSC can be identified by the length of x or y semiaxis of ellipsoid. Meanwhile, the concurrence is related to the lengths of x and z semiaxes of QSE. The information can flow bidirectionally between the qubit system and the non-Markovian environment, which can induce the shrink, inflation and movement of ellipsoid in the Bloch sphere. On the contrary, due to the decoherence of information within Markovian environment, the QSE gradually shrinks and then eventually disappears in the north pole of Bloch sphere. Therefore, the evolutions of MSC and concurrence can be mapped by the aforementioned dynamics of QSE. The results also reveal that MSC and concurrence can be enhanced by suppressing the degradation of ellipsoid’s semiaxis. Moreover, we investigate the inflation of QSE under filtering operation and derive the condition of increasing MSC. An optimal operation strength of filtering operation is also obtained. It is worth noting that MSC and concurrence can be frozen by the optimal strength in the strong coupling and weak coupling regimes.

Transverse flux permanent magnet motor has the characteristics of high torque density, good fault tolerance, easy control, etc. In this paper, a four-phase transverse flux permanent magnet motor is taken as the control object. Based on the PR regulator, the current loop is designed to control the AC current, achieving excellent current following performance. Meanwhile, the control system algorithm is simple, reducing multiple rotation coordinate transformation compared with traditional permanent magnet synchronous motors vector control system. In this paper, the control system is simulated and verified based on Simulink. The results show that the control system can achieve excellent dynamic performance and stable performance.

The quasi-one-dimensional (quasi-1D) TaSe3 attracts considerable attention for its intriguing superconductivity and possible interplay with nontrivial topology and charge density wave (CDW) state. However, unlike the isostructural analogues, CDW has not been observed for TaSe3 despite its quasi-1D character that is supposed to promote Peierls instabilities and CDW. Here we synthesize TaSe3 mesowires (MWs) using a one-step approach. For the MW of ~300 nm thick, a distinct CDW transition occurs at 65 K in the resistivity measurement, which has not been reported before and is further evidenced by the Raman characterization and susceptibility measurement. For comparison, we have also prepared bulk single crystal TaSe3. Although no anomaly appears in the resistivity and magnetoresistance measurements, the carrier type detected by Hall effect varies from n-type to p-type below 50 K, suggesting a reconstruction of Fermi surface that could be associated with CDW. The enhancement of CDW in the MWs is attributed to the reduced dimensionality. TaSe3 is demonstrated to be a promising platform to study the correlation and competition of CDW and superconductivity in the quasi-1D systems., 21 pages, 5 figures, Applied Physics Letters

We study the quantum critical phenomena emerging at the transition from triple-Weyl semimetal to band insulator, which is a topological phase transition described by the change of topological invariant. The critical point realizes a new type of semimetal state in which the fermion dispersion is cubic along two directions and quadratic along the third. Our renormalization group analysis reveals that, the Coulomb interaction is marginal at low energies and even arbitrarily weak Coulomb interaction suffices to induce an infrared fixed point. We compute a number of observable quantities, and show that they all exhibit non-Fermi liquid behaviors at the fixed point. When the interplay between the Coulomb and short-range four-fermion interactions is considered, the system becomes unstable below a finite energy scale. The system undergoes a first-order topological transition when the fermion flavor $N$ is small, and enters into a nematic phase if $N$ is large enough. Non-Fermi liquid behaviors are hidden by the instability at low temperatures, but can still be observed at higher temperatures. Experimental detection of the predicted phenomena is discussed., Comment: 24 pages, 10 figures, 3 table

Quantum steering ellipsoid has been regarded as a faithful representation of arbitrary two-qubit state and provides a visualized geometry for quantum resources. Herein, considering two-qubit X states, the generally form of quantum steering ellipsoid is derived. It shows the l1 norm of coherence can be visually denoted by the x or y semiaxis length of the ellipsoid. By using ellipsoid with largest volume, we obtain the upper bounds of the l1 norm and relative entropy of coherence for two-qubit X states. We also reveal that the dynamics of l1 norm of coherence can be exhibited by the evolution of quantum steering ellipsoid under noisy channels. In addition, the expression of Bell-nonlocality for two-qubit X states is provided in the frame of quantum steering ellipsoids, and this expression is relevant to semiaxis lengths of ellipsoid. Based on this, we investigate relationship between the l1 norm of coherence and Bell-nonlocality. Notably, Bell-nonlocality of two-qubit X states can be detected according to the l1 norm of coherence. Finally, Bell-nonlocality and l1 norm of coherence for two-qubit Heisenberg spin-1/2 XX model with inhomogeneous field are researched as a verification of our results.

Quantum steering describes the phenomenon that one system can be immediately influenced by another with local measurements. It can be detected by the violation of a powerful and useful steering criterion from general entropic uncertainty relation. This criterion, in principle, can be evaluated straightforwardly and achieved by only probability distributions from a finite set of measurement settings. Herein, we experimentally verify the steering criterion by means of the two-photon Werner-like states and three Pauli measurements. The results indicate that quantum steering can be verified by the criterion in a convenient way. In particular, it is no need to perform the usual quantum state tomography in experiment, which reduces the required experimental resources greatly. Moreover, we demonstrate that the criterion is stronger than the linear one for the detecting quantum steering of the Werner-like states., Comment: 6 pages, 3 figures, 4 tables, submitted to Phys. Rev. A on 19th August, 2019 (Under review)

The extraordinary superconductivity has been observed in a pressurized commercial niobium-titanium alloy. Its zero-resistance superconductivity persists from ambient pressure to the pressure as high as 261.7 GPa, a record-high pressure up to which a known superconducting state can continuously survive. Remarkably, at such an ultra-high pressure, although the ambient pressure volume is shrunk by 45% without structural phase transition, the superconducting transition temperature (TC ) increases to ≈19.1 K from ≈9.6 K, and the critical magnetic field (HC2 ) at 1.8 K has been enhanced to 19 T from 15.4 T. These results set new records for both the TC and the HC2 among all the known alloy superconductors composed of only transition metal elements. The remarkable high-pressure superconducting properties observed in the niobium-titanium alloy not only expand the knowledge on this important commercial superconductor but also are helpful for a better understanding on the superconducting mechanism.

Taking into account the interplay between the disorder and Coulomb interaction, the phase diagram of three-dimensional anisotropic Weyl semimetal is studied by renormalization group theory. Weak disorder is irrelevant in anisotropic Weyl semimetal, while the disorder becomes relevant and drives a quantum phase transition from semimetal to compressible diffusive metal phases if the disorder strength is larger than a critical value. The long-range Coulomb interaction is irrelevant in clean anisotropic Weyl semimetal. However, interestingly, we find that the long-range Coulomb interaction exerts a dramatic influence on the critical disorder strength for phase transition to compressible diffusive metal. Specifically, the critical disorder strength can receive a prominent change even though an arbitrarily weak Coulomb interaction is included. This novel behavior is closely related to the anisotropic screening effect of Coulomb interaction,and essentially results from the specifical energy dispersion of the fermion excitations in anisotropic Weyl semimetal. The theoretical results are helpful for understanding the physical properties of the candidates of anisotropic Weyl semimetal, such as pressured BiTeI, and some other related materials., 27 pages, 22 figures

CuO mesocrystal entangled with multi-wall carbon nanotube (MWCNT) composites are synthesized through a facile scalable precipitation and a followed oriented aggregation process. When evaluated as anode materials for lithium ion batteries, the CuO-MWCNT composites exhibit high areal capacity and good cycling stability (1.11 mA h cm −2 after 400 cycles at the current density of 0.39 mA cm −2 ). The excellent electrochemical performance can be ascribed to the synergy effect of the unique structure of defect-rich CuO mesocrystals and the flexible conductive MWCNTs. The assembled architecture of CuO mesocrystals can favor the Li-ion transport and accommodate the volume change effectively, as well as possess the structural and chemical stability of bulk materials, while the entangled MWCNTs can maintain the structural and electrical integrity of the electrode during the cycles.

Superconducting Cu x TaSe2(x=0.05, 0.15) and Cu0.15TaSe2−x S x (x=0, 0.5, 1, 1.5) single crystals have been systematically fabricated by a chemical vapor transport method. It is found that the double doping in TaSe2, i.e., the simultaneous intercalation of Cu and substitution of Se by S, can substantially enhance the superconducting transition temperature. Transport property measurements give evidence of the coexistence and competition of charge density wave state and superconductivity in Cu x TaSe2 which provide meaningful information to understand the complex electronic states in this system. The parallel shift and the fan-shape broadening behaviors are observed in the superconducting transition curves under magnetic fields of Cu0.15TaSeS and TaSeS, respectively, indicating an increase of coherence length and suppression of superconducting fluctuation induced by copper intercalation.