The physical fundamentals and influences upon electrode materials' open-circuit voltage (OCV) and the spatial distribution of electrochemical potential in the full cell are briefly reviewed. We hope to illustrate that a better understanding of these scientific problems can help to develop and design high voltage cathodes and interfaces with low Ohmic drop. OCV is one of the main indices to evaluate the performance of lithium ion batteries (LIBs), and the enhancement of OCV shows promise as a way to increase the energy density. Besides, the severe potential drop at the interfaces indicates high resistance there, which is one of the key factors limiting power density.
ISSN: 2058-3834
Chinese Physics B is an international journal covering the latest developments and achievements in all branches of physics (with the exception of nuclear physics and physics of elementary particles and fields, which is covered by Chinese Physics C).
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Zi-Yi Chen et al 2023 Chinese Phys. B 32 118104
The prediction of chemical synthesis pathways plays a pivotal role in materials science research. Challenges, such as the complexity of synthesis pathways and the lack of comprehensive datasets, currently hinder our ability to predict these chemical processes accurately. However, recent advancements in generative artificial intelligence (GAI), including automated text generation and question–answering systems, coupled with fine-tuning techniques, have facilitated the deployment of large-scale AI models tailored to specific domains. In this study, we harness the power of the LLaMA2-7B model and enhance it through a learning process that incorporates 13878 pieces of structured material knowledge data. This specialized AI model, named MatChat, focuses on predicting inorganic material synthesis pathways. MatChat exhibits remarkable proficiency in generating and reasoning with knowledge in materials science. Although MatChat requires further refinement to meet the diverse material design needs, this research undeniably highlights its impressive reasoning capabilities and innovative potential in materials science. MatChat is now accessible online and open for use, with both the model and its application framework available as open source. This study establishes a robust foundation for collaborative innovation in the integration of generative AI in materials science.
Limin Cang et al 2022 Chinese Phys. B 31 038402
The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.
Chen Fang et al 2016 Chinese Phys. B 25 117106
We review the recent, mainly theoretical, progress in the study of topological nodal line semimetals in three dimensions. In these semimetals, the conduction and the valence bands cross each other along a one-dimensional curve in the three-dimensional Brillouin zone, and any perturbation that preserves a certain symmetry group (generated by either spatial symmetries or time-reversal symmetry) cannot remove this crossing line and open a full direct gap between the two bands. The nodal line(s) is hence topologically protected by the symmetry group, and can be associated with a topological invariant. In this review, (i) we enumerate the symmetry groups that may protect a topological nodal line; (ii) we write down the explicit form of the topological invariant for each of these symmetry groups in terms of the wave functions on the Fermi surface, establishing a topological classification; (iii) for certain classes, we review the proposals for the realization of these semimetals in real materials; (iv) we discuss different scenarios that when the protecting symmetry is broken, how a topological nodal line semimetal becomes Weyl semimetals, Dirac semimetals, and other topological phases; and (v) we discuss the possible physical effects accessible to experimental probes in these materials.
Xiaoling Wu et al 2021 Chinese Phys. B 30 020305
Quantum information processing based on Rydberg atoms emerged as a promising direction two decades ago. Recent experimental and theoretical progresses have shined exciting light on this avenue. In this concise review, we will briefly introduce the basics of Rydberg atoms and their recent applications in associated areas of neutral atom quantum computation and simulation. We shall also include related discussions on quantum optics with Rydberg atomic ensembles, which are increasingly used to explore quantum computation and quantum simulation with photons.
Min Hong et al 2018 Chinese Phys. B 27 048403
Thermoelectric materials, enabling the directing conversion between heat and electricity, are one of the promising candidates for overcoming environmental pollution and the upcoming energy shortage caused by the over-consumption of fossil fuels. Bi2Te3-based alloys are the classical thermoelectric materials working near room temperature. Due to the intensive theoretical investigations and experimental demonstrations, significant progress has been achieved to enhance the thermoelectric performance of Bi2Te3-based thermoelectric materials. In this review, we first explored the fundamentals of thermoelectric effect and derived the equations for thermoelectric properties. On this basis, we studied the effect of material parameters on thermoelectric properties. Then, we analyzed the features of Bi2Te3-based thermoelectric materials, including the lattice defects, anisotropic behavior and the strong bipolar conduction at relatively high temperature. Then we accordingly summarized the strategies for enhancing the thermoelectric performance, including point defect engineering, texture alignment, and band gap enlargement. Moreover, we highlighted the progress in decreasing thermal conductivity using nanostructures fabricated by solution grown method, ball milling, and melt spinning. Lastly, we employed modeling analysis to uncover the principles of anisotropy behavior and the achieved enhancement in Bi2Te3, which will enlighten the enhancement of thermoelectric performance in broader materials
Jingyuan Zhong et al 2023 Chinese Phys. B 32 047203
The planar Hall effect (PHE), which originates from anisotropic magnetoresistance, presents a qualitative and simple approach to characterize electronic structures of quantum materials by applying an in-plane rotating magnetic field to induce identical oscillations in both longitudinal and transverse resistances. In this review, we focus on the recent research on the PHE in various quantum materials, including ferromagnetic materials, topological insulators, Weyl semimetals, and orbital anisotropic matters. Firstly, we briefly introduce the family of Hall effect and give a basic deduction of PHE formula with the second-order resistance tensor, showing the mechanism of the characteristic π-period oscillation in trigonometric function form with a π/4 phase delay between the longitudinal and transverse resistances. Then, we will introduce the four main mechanisms to realize PHE in quantum materials. After that, the origin of the anomalous planar Hall effect (APHE) results, of which the curve shapes deviate from that of PHE, will be reviewed and discussed. Finally, the challenges and prospects for this field of study are discussed.
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Zhi-Hao Yang and Yan-Long Yang 2024 Chinese Phys. B 33 050203
In evolutionary games, most studies on finite populations have focused on a single updating mechanism. However, given the differences in individual cognition, individuals may change their strategies according to different updating mechanisms. For this reason, we consider two different aspiration-driven updating mechanisms in structured populations: satisfied-stay unsatisfied shift (SSUS) and satisfied-cooperate unsatisfied defect (SCUD). To simulate the game player's learning process, this paper improves the particle swarm optimization algorithm, which will be used to simulate the game player's strategy selection, i.e., population particle swarm optimization (PPSO) algorithms. We find that in the prisoner's dilemma, the conditions that SSUS facilitates the evolution of cooperation do not enable cooperation to emerge. In contrast, SCUD conditions that promote the evolution of cooperation enable cooperation to emerge. In addition, the invasion of SCUD individuals helps promote cooperation among SSUS individuals. Simulated by the PPSO algorithm, the theoretical approximation results are found to be consistent with the trend of change in the simulation results.
Haoran Yan et al 2024 Chinese Phys. B 33 058801
The Hodgkin–Huxley model assumes independent ion channel activation, although mutual interactions are common in biological systems. This raises the problem why neurons would favor independent over cooperative channel activation. In this study, we evaluate how cooperative activation of sodium channels affects the neuron's information processing and energy consumption. Simulations of the stochastic Hodgkin–Huxley model with cooperative activation of sodium channels show that, while cooperative activation enhances neuronal information processing capacity, it greatly increases the neuron's energy consumption. As a result, cooperative activation of sodium channel degrades the energy efficiency for neuronal information processing. This discovery improves our understanding of the design principles for neural systems, and may provide insights into future designs of the neuromorphic computing devices as well as systematic understanding of pathological mechanisms for neural diseases.
Fu-Zhong Nian and Yu Yang 2024 Chinese Phys. B 33 058705
Despite having significant effects on social contagions, individual heterogeneity has frequently been overlooked in earlier studies. To better understand the complexity of social contagions, a non-Markovian model incorporating heterogeneous social influence and adoption thresholds is introduced. For theoretical analysis, a generalized edge-based compartmental theory which considers the heterogeneities of social influence and adoption thresholds is developed. Focusing on the final adoption size, the critical propagation probability, and the phase transition type, social contagions for adoption thresholds that follow normal distributions with various standard deviations, follow various distributions, and correlate with degrees are investigated. When thresholds follow normal distributions, a larger standard deviation results in a larger final adoption size when the information propagation probability is relatively low. However, when the information propagation probability is relatively high, a larger standard deviation results in a smaller final adoption size. When thresholds follow various distributions, crossover phenomena in phase transition are observed when investigating the relationship of the final adoption size versus the average adoption threshold for some threshold distributions. When thresholds are correlated with degrees, similar crossover phenomena occur when investigating the relationship of the final adoption size versus the degree correlation index. Additionally, we find that increasing the heterogeneity of social influence suppresses the effects of adoption threshold heterogeneity on social contagions in three cases. Our theory predictions agree well with the simulation results.
Qin Gao and Ping-Wei Zheng 2024 Chinese Phys. B 33 055202
Through theoretical analysis, we construct a physical model that includes the influence of counter-external driven current opposite to the plasma current direction in the neoclassical tearing mode (NTM). The equation is used with this model to obtain the modified Rutherford equation with co-current and counter-current contributions. Consistent with the reported experimental results, numerical simulations have shown that the localized counter external current can only partially suppress NTM when it is far from the resonant magnetic surface. Under some circumstances, the Ohkawa mechanism dominated current drive (OKCD) by electron cyclotron waves can concurrently create both co-current and counter-current. In this instance, the minimal electron cyclotron wave power that suppresses a particular NTM was calculated by the Rutherford equation. The result is marginally less than when taking co-current alone into consideration. As a result, to suppress NTM using OKCD, one only needs to align the co-current with a greater OKCD peak well with the resonant magnetic surface. The effect of its lower counter-current does not need to be considered because the location of the counter-current deviates greatly from the resonant magnetic surface.
Shao-Hua Xiang et al 2024 Chinese Phys. B 33 050309
The non-Gaussianity of quantum states incarnates an important resource for improving the performance of continuous-variable quantum information protocols. We propose a novel criterion of non-Gaussianity for single-mode rotationally symmetric quantum states via the squared Frobenius norm of higher-order cumulant matrix for the quadrature distribution function. As an application, we study the non-Gaussianities of three classes of single-mode symmetric non-Gaussian states: a mixture of vacuum and Fock states, single-photon added thermal states, and even/odd Schrödinger cat states. It is shown that such a criterion is faithful and effective for revealing non-Gaussianity. We further extend this criterion to two cases of symmetric multi-mode non-Gaussian states and non-symmetric single-mode non-Gaussian states.
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Hongxin Chen et al 2024 Chinese Phys. B 33 047304
The anomalous valley Hall effect (AVHE) can be used to explore and utilize valley degrees of freedom in materials, which has potential applications in fields such as information storage, quantum computing and optoelectronics. AVHE exists in two-dimensional (2D) materials possessing valley polarization (VP), and such 2D materials usually belong to the hexagonal honeycomb lattice. Therefore, it is necessary to achieve valleytronic materials with VP that are more readily to be synthesized and applicated experimentally. In this topical review, we introduce recent developments on realizing VP as well as AVHE through different methods, i.e., doping transition metal atoms, building ferrovalley heterostructures and searching for ferrovalley materials. Moreover, 2D ferrovalley systems under external modulation are also discussed. 2D valleytronic materials with AVHE demonstrate excellent performance and potential applications, which offer the possibility of realizing novel low-energy-consuming devices, facilitating further development of device technology, realizing miniaturization and enhancing functionality of them.
Qiwen Qu et al 2024 Chinese Phys. B 33 047803
Besides the diverse investigations on the interactions between intense laser fields and molecular systems, extensive research has been recently dedicated to exploring the response of nanosystems excited by well-tailored femtosecond laser fields. Due to the fact that nanostructures hold peculiar effects when illuminated by laser pulses, the underlying mechanisms and the corresponding potential applications can make significant improvements in both fundamental research and development of novel techniques. In this review, we provide a summarization of the strong field ionization occurring on the surface of nanosystems. The molecules attached to the nanoparticle surface perform as the precursor in the ionization and excitation of the whole nanosystem, the fundamental processes of which are yet to be discovered. We discuss the influence on nanoparticle constituents, geometric shapes and sizes, as well as the specific waveforms of the excitation laser fields. The intriguing characteristics observed in surface ion emission reflect how enhanced near field affects the localized ionizations and nanoplasma expansions, thereby paving the way for further precision controls on the light-and-matter interactions in the extreme spatial temporal levels.
Yubo Yang et al 2024 Chinese Phys. B 33 030702
AI development has brought great success to upgrading the information age. At the same time, the large-scale artificial neural network for building AI systems is thirsty for computing power, which is barely satisfied by the conventional computing hardware. In the post-Moore era, the increase in computing power brought about by the size reduction of CMOS in very large-scale integrated circuits (VLSIC) is challenging to meet the growing demand for AI computing power. To address the issue, technical approaches like neuromorphic computing attract great attention because of their feature of breaking Von-Neumann architecture, and dealing with AI algorithms much more parallelly and energy efficiently. Inspired by the human neural network architecture, neuromorphic computing hardware is brought to life based on novel artificial neurons constructed by new materials or devices. Although it is relatively difficult to deploy a training process in the neuromorphic architecture like spiking neural network (SNN), the development in this field has incubated promising technologies like in-sensor computing, which brings new opportunities for multidisciplinary research, including the field of optoelectronic materials and devices, artificial neural networks, and microelectronics integration technology. The vision chips based on the architectures could reduce unnecessary data transfer and realize fast and energy-efficient visual cognitive processing. This paper reviews firstly the architectures and algorithms of SNN, and artificial neuron devices supporting neuromorphic computing, then the recent progress of in-sensor computing vision chips, which all will promote the development of AI.
Yanan Dai 2024 Chinese Phys. B 33 038703
Exploring the realms of physics that extend beyond thermal equilibrium has emerged as a crucial branch of condensed matter physics research. It aims to unravel the intricate processes involving the excitations, interactions, and annihilations of quasi- and many-body particles, and ultimately to achieve the manipulation and engineering of exotic non-equilibrium quantum phases on the ultrasmall and ultrafast spatiotemporal scales. Given the inherent complexities arising from many-body dynamics, it therefore seeks a technique that has efficient and diverse detection degrees of freedom to study the underlying physics. By combining high-power femtosecond lasers with real- or momentum-space photoemission electron microscopy (PEEM), imaging excited state phenomena from multiple perspectives, including time, real space, energy, momentum, and spin, can be conveniently achieved, making it a unique technique in studying physics out of equilibrium. In this context, we overview the working principle and technical advances of the PEEM apparatus and the related laser systems, and survey key excited-state phenomena probed through this surface-sensitive methodology, including the ultrafast dynamics of electrons, excitons, plasmons, spins, etc., in materials ranging from bulk and nano-structured metals and semiconductors to low-dimensional quantum materials. Through this review, one can further envision that time-resolved PEEM will open new avenues for investigating a variety of classical and quantum phenomena in a multidimensional parameter space, offering unprecedented and comprehensive insights into important questions in the field of condensed matter physics.
Juan-Juan Wang and Jun Wang 2024 Chinese Phys. B 33 017801
Valleytronics is an emergent discipline in condensed matter physics and offers a new way to encode and manipulate information based on the valley degree of freedom in materials. Among the various materials being studied, Kekulé distorted graphene has emerged as a promising material for valleytronics applications. Graphene can be artificially distorted to form the Kekulé structures rendering the valley-related interaction. In this work, we review the recent progress of research on Kekulé structures of graphene and focus on the modified electronic bands due to different Kekulé distortions as well as their effects on the transport properties of electrons. We systematically discuss how the valley-related interaction in the Kekulé structures was used to control and affect the valley transport including the valley generation, manipulation, and detection. This article summarizes the current challenges and prospects for further research on Kekulé distorted graphene and its potential applications in valleytronics.
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You Zou et al 2019 Chinese Phys. B 28 035203
We have investigated the flux symmetry on the capsule in a six-cylinder-port hohlraum for improving the design of the hohlraum. The influence factors of drive symmetry on the capsule in the hohlraum are studied, including laser power, laser beams arrangement, hohlraum geometric parameters, plasma condition, capsule convergence, etc. The x-ray radiation flux distribution on the capsule is obtained based on the three-dimensional view factor model. In the six-cylinder-port hohlraum, the main drive asymmetry is the C40 mode asymmetry. When the C40 mode asymmetry approaches zero, the drive symmetry on the capsule is optimal. Our results demonstrate that in order to have a high flux symmetry on the capsule in the laser main-pulse stage, more negative initial C40 modes are needed, which can be realized by adjusting the hohlraum geometry parameters. The hohlraum with column length LH = 4.81 mm has an optimal symmetry in the laser main-pulse stage.
Dong-Liang Yang et al 2019 Chinese Phys. B 28 036201
The structural phase transitions of bismuth under rapid compression has been investigated in a dynamic diamond anvil cell using time-resolved synchrotron x-ray diffraction. As the pressure increases, the transformations from phase I, to phase II, to phase III, and then to phase V have been observed under different compression rates at 300 K. Compared with static compression results, no new phase transition sequence appears under rapid compression at compression rate from 0.20 GPa/s to 183.8 GPa/s. However, during the process across the transition from phase III to phase V, the volume fraction of product phase as a function of pressure can be well fitted by a compression-rate-dependent sigmoidal curve. The resulting parameters indicate that the activation energy related to this phase transition, as well as the onset transition pressure, shows a compression-rate-dependent performance. A strong dependence of over-pressurization on compression rate occurs under rapid compression. A formula for over-pressure has been proposed, which can be used to quantify the over-pressurization.
Bin-Bin Fu et al 2019 Chinese Phys. B 28 037103
Topological Dirac semimetals (DSMs) present a kind of topologically nontrivial quantum state of matter, which has massless Dirac fermions in the bulk and topologically protected states on certain surfaces. In superconducting DSMs, the effects of their nontrivial topology on superconducting pairing could realize topological superconductivity in the bulk or on the surface. As superconducting pairing takes place at the Fermi level EF, to make the effects possible, the Dirac points should lie in the vicinity of EF so that the topological electronic states can participate in the superconducting paring. Here, we show using angle-resolved photoelectron spectroscopy that in a series of (Ir1−xPtx)Te2 compounds, the type-II Dirac points reside around EF in the superconducting region, in which the bulk superconductivity has a maximum Tc of ∼ 3 K. The realization of the coexistence of bulk superconductivity and low-energy Dirac fermions in (Ir1−xPtx)Te2 paves the way for studying the effects of the nontrivial topology in DSMs on the superconducting state.
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Duan et al
Seeking intrinsically low thermal conductivity materials is a viable strategy in the pursuit of high-performance thermoelectric materials. Here, by using first-principles calculations and semiclassical Boltzmann transport theory, we systemically investigate the carrier transport and thermoelectric properties of monolayer Janus GaInX3 (X = S; Se; Te). It is found that the lattice thermal conductivities can reach values as low as 3.07 Wm−1K−1, 1.16 Wm−1K−1 and 0.57 Wm−1K−1 for GaInS3, GaInSe3, and GaInTe3, respectively, at room temperature. These notably low thermal conductivity is attributed to strong acoustic-optical phonon coupling caused by the presence of low-frequency optical phonons in GaInX3 materials. Furthermore, by integrating the characteristics of electronic and thermal transport, the dimensionless figure of merit ZT can reach maximum values of 0.95, 2.37, and 3.00 for GaInS3, GaInSe3, and GaInTe3, respectively. Our results suggest monolayer Janus GaInX3 (X = S; Se; Te) are promising candidates for thermoelectric and heat management applications.
Rao et al
The propagation of dust ion acoustic solitary wave (DIASW) is investigated in the multicomponent dusty plasma with adiabatic ions, superthermal electrons and stationary dust. The reductive perturbation method is employed to derive the damped Korteweg-de Vries (DKdV) equation which describes DIASW. The result reveals that, the adiabaticity of ions significantly modifies the basic features of the DIASW. The ionization effect makes the solitary wave growing, while collisions reduce the growth rate and even lead to the damping. With the increase in ionization cross section $\frac{{\Delta \sigma }}{{{\sigma _0}}}$, ion-to-electron density ratio ${{\delta}_{\rm{ie}}}$ and superthermal electrons parameter $\kappa $, the effect of ionization on DIASW enhances.
Wang et al
FL-Online (http://fanlab.ac.cn) is an out-of-box modern web service featuring a user-friendly interface and simplified parameters, providing academic users with access to a series of online programs for biomolecular crystallography, including SAPI-online, OASIS-online, C-IPCAS-online and a series of upcoming software releases. Meanwhile, it is a highly scalable and maintainable web application framework, that provides a powerful and flexible solution for academic web development needs. All the codes are open-source under MIT licenses in GitHub.
Geng et al
The interconnection bottleneck caused by limitations of cable number, inner space and cooling power of dilution refrigerators has been an outstanding challenge for building scalable superconducting quantum computers with the increasing number of qubits in quantum processors. To surmount such an obstacle, it is desirable to integrate qubits with quantum-classical interface (QCI) circuits based on rapid single flux quantum (RSFQ) circuits. In this work, a digital flux tuner for qubits (DFTQ) is proposed for manipulating flux of qubits as a crucial part of the interface circuit. A schematic diagram of the DFTQ is presented, consisting of a coarse tuning unit and a fine-tuning unit for providing magnetic flux with different precision to qubits. The method of using DFTQ to provide flux for gate operations is discussed from the optimization of circuit design and input signal. To verify the effectiveness of the method, simulations of a single DFTQ and quantum gates including a Z gate and an iSWAP gate with DFTQs are performed for flux-tunable transmons. The quantum process tomography corresponding to the two gates is also carried out to analyze the sources of gate error. The results of tomography show that the gate fidelities independent on initial states of the Z gate and the iSWAP gate are 99.935% and 99.676%, respectively. With DFTQs inside, the QCI would be a powerful tool for building large-scale quantum computers.
Kuncan et al
Aerogel nanoporous materials possess high porosity, high specific surface area, and extremely low density due to their unique nanoscale network structure. Moreover, their effective thermal conductivity is very l1ow, making them a new type of lightweight and highly efficient nanoscale super-insulating material. However, predicting their effective thermal conductivity is challenging due to their uneven pore size distribution. To investigate the internal heat transfer mechanism of aerogel nanoporous materials, this study constructed cross-aligned and cubic pore model (CACPM) based on the actual pore arrangement of SiO2 aerogel. Based on the established cross-aligned and cubic pore model (CACPM), the effective thermal conductivity expression for aerogel was derived by simultaneously considering gas-phase heat conduction, solid-phase heat conduction, and radiative heat transfer. The derived expression was then compared with available experimental data and the Wei structure model. The results indicate that, according to the model established in this study for the derived thermal conductivity formula of silica aerogel, for powdery silica aerogel under the conditions of T=298K, a2=0.85, D1=90μm, ρ=128kg/m3, within the pressure range of 0-105Pa, the average deviation between the calculated values and experimental values is 10.51%. In the pressure range of 103-104Pa, the deviation between calculated values and experimental values is within 4%. Under these conditions, the model has certain reference value in engineering verification. This study also makes a certain contribution to the research of aerogel thermal conductivity heat transfer model and calculation formula.