The phenomenon of group motion is common in nature,ranging from the schools of fish,birds and insects,to avalanches,landslides and sand drift.If we treat objects as collectively moving particles,such phenomena can be ...The phenomenon of group motion is common in nature,ranging from the schools of fish,birds and insects,to avalanches,landslides and sand drift.If we treat objects as collectively moving particles,such phenomena can be studied from a physical point of view,and the research on many-body systems has proved that marvelous effects can arise from the simplest individuals.The motion of numerous individuals presents different dynamic phases related to the ordering of the system.However,it is usually difficult to study the dynamic ordering and its transitions through experiments.Electron bubble states formed in a two-dimensional electron gas,as a type of electron solids,can be driven by an external electric field and provide a platform to study the dynamic collective behaviors.Here,we demonstrate that the noise spectrum is a powerful method to investigate the dynamics of bubble states.We observed not only the phenomena of dynamically ordered and disordered structures,but also unexpected alternations between them.Our results show that a dissipative system can convert between chaotic structures and ordered structures when tuning global parameters,which is concealed in conventional transport measurements of resistance or conductance.Moreover,charging the objects to study the electrical noise spectrum in collective motions can be an additional approach to revealing dynamic ordering transitions.展开更多
L1_(0)-FePt nanoparticles(NPs)are urgently anticipated because of their promising applications.However,the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge.Inspired by ...L1_(0)-FePt nanoparticles(NPs)are urgently anticipated because of their promising applications.However,the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge.Inspired by recent studies on the effect of vacancy defects on structural ordering,we proposed an intentional vacancy defect design strategy for directly synthesizing highly ordered FePt NPs.In the present work,we used the first-principle calculations to investigate the influence of doping typical elements(Cu,Ag,and Pb)on the vacancy formation energy(E_(vac))of FePt NPs.The vacancy defects were effectively formed by introducing elements of larger atomic radii and higher propensity for segregation into the FePt lattice,facilitating the diffusion of Fe and Pt atoms.The Pb doping showed remarkable efficacy in promoting the ordering transition.Experimentally,wet-chemical synthesis confirmed the success of the proposed strategy in achieving highly ordered L1_(0)-FePt NPs with exceptional magnetic properties and super-fine size(ordering degree of 0.896,impressive coercivity of 21.74 kOe,and small particle size of 9.02 nm).Additionally,we have deduced a diffusion model elucidating the formation process of the ordered FePt NPs,focusing on the migration of Pb atoms from the center to the surface of the particles.This migration is demonstrated to generate more vacancies and promote the transition to the ordered L1_(0)-FePt phase.The findings of this research offer valuable insights into synthesizing highly ordered and ultrafine L1_(0)-type nanomaterials.展开更多
Phase transitions,as one of the most intriguing phenomena in nature,are divided into first-order phase transitions(FOPTs)and continuous ones in current classification.While the latter shows striking phenomena of scali...Phase transitions,as one of the most intriguing phenomena in nature,are divided into first-order phase transitions(FOPTs)and continuous ones in current classification.While the latter shows striking phenomena of scaling and universality,the former has recently also been demonstrated to exhibit scaling and universal behavior within a mesoscopic,coarse-grained Landau-Ginzburg theory.Here we apply this theory to a microscopic model-the paradigmatic Ising model,which undergoes FOPTs between two ordered phases below its critical temperature-and unambiguously demonstrate universal scaling behavior in such FOPTs.These results open the door for extending the theory to other microscopic FOPT systems and experimentally testing them to systematically uncover their scaling and universal behavior.展开更多
High quality single crystal CaFe4As3 was grown by using the Sn flux method. Unlike layered CaFe2As2, CaFe4As3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed...High quality single crystal CaFe4As3 was grown by using the Sn flux method. Unlike layered CaFe2As2, CaFe4As3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed at - 90 K and - 27 K, respectively. The high temperature transition is an antiferromagnetic（AF） ordering transition. However, the low temperature transition shows complex properties. It shows a ferromagnetic-like transition when a field is applied along b-axis, while antiferromagnetism-like transition when a field is applied perpendicular to b-axis. These results suggest that the low temperature transition at 27 K is a first-order transition from an AF state to a canted AF state. In addition, the low temperature electron specific heat coefficient reaches as high as 143 mJ/mol.K2, showing a heavy fermion behavior.展开更多
We report on the magnetic,magnetocaloric,thermal,and electrical transport properties of Tb_(4)Coln alloy,which crystallizes in two phases,Tb_6Co_(2.1)In_(0.8)(space group Immm)and Tb_(2)In_(0.9)Co_(0.1)(space group P6...We report on the magnetic,magnetocaloric,thermal,and electrical transport properties of Tb_(4)Coln alloy,which crystallizes in two phases,Tb_6Co_(2.1)In_(0.8)(space group Immm)and Tb_(2)In_(0.9)Co_(0.1)(space group P6_(3)/mmc),respectively.The alloy reveals three successive magnetic transitions around T_(1)(163 K),T_(2)(50 K),and T_(3)(29 K),respectively,associated with paramagnetic to ferromagnetic transition and two sequential antiferromagnetic transitions.The low-temperature transition T_(3) follows the first-order magnetic behavior and exhibits the field-induced magnetic transition.Meanwhile,T_(2) and T_(1) are found to be second-order in nature which opens a possibility for hysteresis-free magnetocaloric application.The magnetocaloric properties are determined using different magnetocaloric figures of merits such as-ΔS_(M),ΔT_(ad).RCP,and TEC(10).Additionally,the universal curve behavior in the isothermal entropy change unveils the variation in critical exponents around T_(1) and T_(2) due to the magnetic inhomogeneity in the alloy.Besides,the electrical transport properties of the metallic alloy denote the maximum magnetoresistance of-10%around T_(1).展开更多
The stress relaxation of semi-crystalline nylon 1010 cannot be fitted by the Kohlrausch-Williams-Watts formula when the experiments were performed at pre-yielding regime below the glass transition temperature.We study...The stress relaxation of semi-crystalline nylon 1010 cannot be fitted by the Kohlrausch-Williams-Watts formula when the experiments were performed at pre-yielding regime below the glass transition temperature.We study this problem and identify the two-step mechanism of stress relaxation.At short time scale,relaxation is fast,dominated by stress biased thermal fluctuation with a fixed short-range length scale(activation volume).At long time scale,relaxation is slow due to the emergence of a cooperative long-range length scale determined by the stress fluctuation.The cooperative length scale is proportional to the reciprocal of stress and the amplitude of stress fluctuation is the product of stress and activation volume.Based on this two-step mechanism,we propose a new kinetics equation to capture the stress relaxation effectively,where the short time relaxation is described by an Eyring-like local activation and the long-time relaxation is captured by a cooperative excitation process resorting to an extension from the random first order transition theory.Our equation fits the experimental data well and can serve as a model to guide the related experiments of relaxation processes in crystalline solids.展开更多
An oxide p-n heterojunction composed of Pro.6Ca0.4MnO3 film, with a charge order （CO） transition, and lwt% Nb- doped SrTiO3 substrate is fabricated, and the transport properties of the interface are experimentally s...An oxide p-n heterojunction composed of Pro.6Ca0.4MnO3 film, with a charge order （CO） transition, and lwt% Nb- doped SrTiO3 substrate is fabricated, and the transport properties of the interface are experimentally studied. The rectifying behavior of the junction, well described by the Newman equation, is observed, indicating that tunneling is the dominant process by which the carriers pass through the interface. Above and below the CO transition temperature, satisfactory linear dependencies of junction resistance on temperature are observed, but the slopes of the two resistance-temperature relations are different. The CO process is believed to be relevant to this difference.展开更多
The crowding agent induced phase transition of amphiphilic block copolymers in solution was explicitly considered. The influence of the size and the volume fraction of the crowding agent on the phase separation of amp...The crowding agent induced phase transition of amphiphilic block copolymers in solution was explicitly considered. The influence of the size and the volume fraction of the crowding agent on the phase separation of ampbiphilic diblock copolymers is investigated by using self-consistent field theory （SCFT） method. The concentration of the disorder to order transition of the block copolymer decreases when the size of the crowding agent is larger than that of the solvent. The higher volume fraction of the crowding agent will induce the transition of the block copolymer from disorder to order state at a lower concentration. The relation between the size and the volume fraction of the crowding agent is elucidated. When the size of the crowding agent is larger, its volume fraction of the disorder to order transition of the block copolymer will be lower. The conformation of the crowding agent considered as a polymer chain is also studied and compared.展开更多
Using a Monte Carlo simulation and the single histogram reweighting technique,we study the critical behaviors and phase transitions of the Baxter-Wu(BW)model on a two-layer triangular lattice with Ising-type interlaye...Using a Monte Carlo simulation and the single histogram reweighting technique,we study the critical behaviors and phase transitions of the Baxter-Wu(BW)model on a two-layer triangular lattice with Ising-type interlayer couplings.Via the finite-size analysis,we obtain the transition temperatures and critical exponents at repulsive and attractive interlayer couplings.The data for the repulsive interlayer coupling suggest continuous transitions,and the critical behaviors are the same as those of the 2D BW model,belonging to the four-state Potts universality class.The reduced energy cumulants and the histograms reveal that attractive coupling leads to weak firstorder phase transitions.The pseudocritical exponents with the existence of the interlayer couplings indicate that the first-order transition is very close to the critical point of the 2D standard BW model.展开更多
A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemical potentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe t...A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemical potentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe twoflavor normal quark matter. Depending on whether mo/A, the ratio of dynamical quark mass in vacuum and the 3D momentum cutoff in the loop integrals, is less or greater than 0.413, the phase transition will be of the second or first order. A complete phase diagram of u quark chemical potential versus mo is given. With the electrical neutrality constraint, the region where the second order phase transition happens will be wider than the one without electrical neutrality limitation. The results also show that, for the value ofmo/A from QCD phenomenology, the phase transition must be of the first order.展开更多
The early 21st century finds great change in international order. China＇s foreign relations have entered a new phase where its driving force is rapidly rising for the emerging countries and new global economic govema...The early 21st century finds great change in international order. China＇s foreign relations have entered a new phase where its driving force is rapidly rising for the emerging countries and new global economic govemance mechanism is gradually established. To follow the trend of the times, China has actively participated in global economic govemance and supply of public goods. China＇ s foreign relations present a new vision, idea and strategy under the leadership of President Xi Jinping. It is a new starting point for China to further integrate itself into the world and open itself wider to the world. China takes an active part to participate in global governance and plays an important role in the issues of economic integration, environmental governance, climate change, nuclear nonproliferation, energy crisis, intemet security and anti-terrorism, especially anti-terrorism. This article explains the performance of international relations in current transition order and tries to tackle prior （and in some ways more intractable） issues and to analyze the internal logics and external environment of impact of multi-polarization on China＇s major power diplomacy with its characteristics in the transition of International order.展开更多
The ageing hardening mechanism of a newly designed Fe65Cr13Cu3(CoMnMoNiAlTi)19 medium-entropy stainless alloy(ME-SA)with a simple bcc solid solution matrix was studied.This kind of ME-SA possessed a higher ageing hard...The ageing hardening mechanism of a newly designed Fe65Cr13Cu3(CoMnMoNiAlTi)19 medium-entropy stainless alloy(ME-SA)with a simple bcc solid solution matrix was studied.This kind of ME-SA possessed a higher ageing hardness of approximately 584 HV and higher compressive stress and corrosion resistance than those of the conventional precipitation hardening stainless steel 17-4 PH(Cr17Ni4Cu4 Nb),which has comparable compressive strain.The well-dispersed B2-ordered phase in the cast state transformed to a D03 crystal structure with a higher ordering degree and reduced the precipitate size after ageing at 500℃,thus promoting a great ageing hardening effect.展开更多
The connections between different physical-chemical properties in homologous molecular series are analyzed from the quantum-mechanic and the algebraic theory points of view and are explained by influence of the gage t...The connections between different physical-chemical properties in homologous molecular series are analyzed from the quantum-mechanic and the algebraic theory points of view and are explained by influence of the gage to the quantum electronic continuum. The connection between quantum and macroscopic properties of the substances is confirmed in homologous series of n-alkanes. Linear correlation between the coefficient of magnetization and energy of the highest occupied molecular orbital in homologous series of n-alkanes C2-C10 is established. The connection between diamagnetic and electronic characteristics of n-alkanes with the temperatures of the first order phase transitions （melting point） and other physical-chemical properties were discovered. The nature of interconnection between critical and diamagnetic properties of n-alkanes C2-C10 and results of previous works allow to suppose significant role of the spin interactions in electronic continuum states along the process of the first order phase transitions.展开更多
Magnetic properties and magnetocaloric effect of compound PrFe12B6 are investigated. The coexistence of hard phase PrFe12B6 and soft phase α-Fe causes interesting phenomena on the curves for the temperature dependenc...Magnetic properties and magnetocaloric effect of compound PrFe12B6 are investigated. The coexistence of hard phase PrFe12B6 and soft phase α-Fe causes interesting phenomena on the curves for the temperature dependence of magnetization. PrFe12B6 experiences a first order phase transition at the Curie temperature 206 K, accompanied by an obvious lattice contraction, which in turn results in a large magnetic entropy change. The Maxwell relation fails to give the correct information about magnetic entropy change due to the first order phase transition nature. The large magnetic entropy changes of PrFe12.3B4.7 obtained from heat capacity method are 11.7 and 16.2 J/kg.K for magnetic field changes of 0-2 T and 0-5 T respectively.展开更多
We have investigated the quasinormal modes （QNMs） of phantom scalar perturbation in a Reissner Nordstr6m （RN） background. We find that the dependence of Q, NMs on the mass of the field for the phantom perturbation...We have investigated the quasinormal modes （QNMs） of phantom scalar perturbation in a Reissner Nordstr6m （RN） background. We find that the dependence of Q, NMs on the mass of the field for the phantom perturbation is totally different from that of usual massive perturbation. However, we obtain the same critical value of the overtone number for an angular quantum number from which the mass will begin to have a reverse effect on the real part of QNM frequencies and the perturbation-independent relation between the Q, NMs and the second order thermodynamic phase transition.展开更多
A.M.W. Glass and S.H.McCleary have given the 2 transitive representation of the countable free l group F η(1<η≤ω 0 ).In this paper we shall give the highly ordered transitive representation of count...A.M.W. Glass and S.H.McCleary have given the 2 transitive representation of the countable free l group F η(1<η≤ω 0 ).In this paper we shall give the highly ordered transitive representation of countable free groups on the rational line Q, which generalizes their results. As applications,we obtain the highly ordered transitive representation for the direct product of countable free groups,and the inverse limit of countable free groups must be an action on the set Q.展开更多
Because of. the great needs both for the research of pansystem mathematics andfor the analysis of general things' mechanism, this paper discusses the binary relation,stransitivity confined to multirelation. The so...Because of. the great needs both for the research of pansystem mathematics andfor the analysis of general things' mechanism, this paper discusses the binary relation,stransitivity confined to multirelation. The so-called g-transitvity- a completelynew concept about transitivity- is introduced and its basic properties are investigated.The study shows that it is not only g-transitivity a generalization of traditionaltransitivity, quasi-transitivity, seml-order, quasi-order and other panorder, but alsoincludes many important concepts such as closeness, convexity, topology, duality as itsspecial cases.展开更多
In order to study the basic superconductivity properties of R2Pt3Ge5, we synthesized the single crystalline samples by the Pt–Ge self-flux method. R2Pt3Ge5（R = La, Ce） were also grown for a systematic study. Zero-r...In order to study the basic superconductivity properties of R2Pt3Ge5, we synthesized the single crystalline samples by the Pt–Ge self-flux method. R2Pt3Ge5（R = La, Ce） were also grown for a systematic study. Zero-resistivity was observed in both the La-and Pr-based samples below the reported superconducting transition temperatures. However, magnetic susceptibility measurements showed low superconductivity volume fractions in both La2Pt3Ge5 and R2Pt3Ge5（less than2%）. Ce2Pt3Ge5 did not show any signature of superconductivity. From the specific heat measurements, we did not observe a superconducting transition peak in R2Pt3Ge5, suggesting that it is not a bulk superconductor. The magnetic susceptibility and heat capacity measurements revealed two antiferromagnetic（AFM） orders in R2Pt3Ge5 at T（N1）= 4.2 K and T（N2）= 3.5K, as well as a single AFM transition at TN= 3.8 K in Ce2Pt3Ge5.展开更多
Andrea Corradini,Giovanni Marini&Matteo Calandra Correction to:npj Computational Materials https://doi.org/10.1038/s41524-025-01614-5,published online 26 May 2025“In this article the wrong figure appeared as Fig....Andrea Corradini,Giovanni Marini&Matteo Calandra Correction to:npj Computational Materials https://doi.org/10.1038/s41524-025-01614-5,published online 26 May 2025“In this article the wrong figure appeared as Fig.7;the figure should have appeared as shown below.The original article has been corrected.”展开更多
The recent NANOGrav evidence of a common-source stochastic background provides a hint to gravitational waves(GW)radiation from the Early Universe.We show that this result can be interpreted as a GW spectrum produced f...The recent NANOGrav evidence of a common-source stochastic background provides a hint to gravitational waves(GW)radiation from the Early Universe.We show that this result can be interpreted as a GW spectrum produced from first order phase transitions(FOPTs)around a temperature in the keV-MeV window.Such a class of FOPTs at temperatures much below the electroweak scale can be naturally envisaged in several warm dark matter models such as Majoron dark matter.展开更多
基金The work at PKU was supported by Beijing Natural Science Foundation(Grant No.JQ18002)the NSFC(Grants No.11921005,11674009)+2 种基金the National Key Research and Development Program of China(Grant No.2017YFA0303301)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)The work at Princeton University was funded by the Gordon and Betty Moore Foundation's EPiQS Initiative,Grant GBMF9615 to L.N.Pfeiffer,and by the National Science Foundation MRSEC grant DMR-1420541.
文摘The phenomenon of group motion is common in nature,ranging from the schools of fish,birds and insects,to avalanches,landslides and sand drift.If we treat objects as collectively moving particles,such phenomena can be studied from a physical point of view,and the research on many-body systems has proved that marvelous effects can arise from the simplest individuals.The motion of numerous individuals presents different dynamic phases related to the ordering of the system.However,it is usually difficult to study the dynamic ordering and its transitions through experiments.Electron bubble states formed in a two-dimensional electron gas,as a type of electron solids,can be driven by an external electric field and provide a platform to study the dynamic collective behaviors.Here,we demonstrate that the noise spectrum is a powerful method to investigate the dynamics of bubble states.We observed not only the phenomena of dynamically ordered and disordered structures,but also unexpected alternations between them.Our results show that a dissipative system can convert between chaotic structures and ordered structures when tuning global parameters,which is concealed in conventional transport measurements of resistance or conductance.Moreover,charging the objects to study the electrical noise spectrum in collective motions can be an additional approach to revealing dynamic ordering transitions.
基金supported by the National Key Research and Development Program of China(Nos.2020YFA0907300 and 2021YFB3501404)the National Natural Science Foundation of China(Nos.52301234,52371179,and 52071070)+1 种基金the Doctoral Start-up Foundation of Liaoning Province(No.2023-BS-059)the Fundamental Research Funds for the Central Universities(No.N2309002).
文摘L1_(0)-FePt nanoparticles(NPs)are urgently anticipated because of their promising applications.However,the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge.Inspired by recent studies on the effect of vacancy defects on structural ordering,we proposed an intentional vacancy defect design strategy for directly synthesizing highly ordered FePt NPs.In the present work,we used the first-principle calculations to investigate the influence of doping typical elements(Cu,Ag,and Pb)on the vacancy formation energy(E_(vac))of FePt NPs.The vacancy defects were effectively formed by introducing elements of larger atomic radii and higher propensity for segregation into the FePt lattice,facilitating the diffusion of Fe and Pt atoms.The Pb doping showed remarkable efficacy in promoting the ordering transition.Experimentally,wet-chemical synthesis confirmed the success of the proposed strategy in achieving highly ordered L1_(0)-FePt NPs with exceptional magnetic properties and super-fine size(ordering degree of 0.896,impressive coercivity of 21.74 kOe,and small particle size of 9.02 nm).Additionally,we have deduced a diffusion model elucidating the formation process of the ordered FePt NPs,focusing on the migration of Pb atoms from the center to the surface of the particles.This migration is demonstrated to generate more vacancies and promote the transition to the ordered L1_(0)-FePt phase.The findings of this research offer valuable insights into synthesizing highly ordered and ultrafine L1_(0)-type nanomaterials.
基金supported by the National Natural Science Foundation of China(Grant No.12175316).
文摘Phase transitions,as one of the most intriguing phenomena in nature,are divided into first-order phase transitions(FOPTs)and continuous ones in current classification.While the latter shows striking phenomena of scaling and universality,the former has recently also been demonstrated to exhibit scaling and universal behavior within a mesoscopic,coarse-grained Landau-Ginzburg theory.Here we apply this theory to a microscopic model-the paradigmatic Ising model,which undergoes FOPTs between two ordered phases below its critical temperature-and unambiguously demonstrate universal scaling behavior in such FOPTs.These results open the door for extending the theory to other microscopic FOPT systems and experimentally testing them to systematically uncover their scaling and universal behavior.
基金Project supported by the National Natural Science Foundation of China(Grant No.Y1JA011x11)
文摘High quality single crystal CaFe4As3 was grown by using the Sn flux method. Unlike layered CaFe2As2, CaFe4As3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed at - 90 K and - 27 K, respectively. The high temperature transition is an antiferromagnetic（AF） ordering transition. However, the low temperature transition shows complex properties. It shows a ferromagnetic-like transition when a field is applied along b-axis, while antiferromagnetism-like transition when a field is applied perpendicular to b-axis. These results suggest that the low temperature transition at 27 K is a first-order transition from an AF state to a canted AF state. In addition, the low temperature electron specific heat coefficient reaches as high as 143 mJ/mol.K2, showing a heavy fermion behavior.
基金Project supported by the University Science Park TECHNICOM for Innovation Applications supported by Knowledge Technology (313011D232)supported by the Research&Development Operational Programme funded by the ERDFVEGA1/0705/20,1/0404/21。
文摘We report on the magnetic,magnetocaloric,thermal,and electrical transport properties of Tb_(4)Coln alloy,which crystallizes in two phases,Tb_6Co_(2.1)In_(0.8)(space group Immm)and Tb_(2)In_(0.9)Co_(0.1)(space group P6_(3)/mmc),respectively.The alloy reveals three successive magnetic transitions around T_(1)(163 K),T_(2)(50 K),and T_(3)(29 K),respectively,associated with paramagnetic to ferromagnetic transition and two sequential antiferromagnetic transitions.The low-temperature transition T_(3) follows the first-order magnetic behavior and exhibits the field-induced magnetic transition.Meanwhile,T_(2) and T_(1) are found to be second-order in nature which opens a possibility for hysteresis-free magnetocaloric application.The magnetocaloric properties are determined using different magnetocaloric figures of merits such as-ΔS_(M),ΔT_(ad).RCP,and TEC(10).Additionally,the universal curve behavior in the isothermal entropy change unveils the variation in critical exponents around T_(1) and T_(2) due to the magnetic inhomogeneity in the alloy.Besides,the electrical transport properties of the metallic alloy denote the maximum magnetoresistance of-10%around T_(1).
基金financially supported by the National Natural Science Foundation of China (Nos.21873054,21774131 and 21544007)the National Natural Science Foundation of China (Nos.U1862205 and 51673110)China Petroleum & Chemical Corporation for financial support。
文摘The stress relaxation of semi-crystalline nylon 1010 cannot be fitted by the Kohlrausch-Williams-Watts formula when the experiments were performed at pre-yielding regime below the glass transition temperature.We study this problem and identify the two-step mechanism of stress relaxation.At short time scale,relaxation is fast,dominated by stress biased thermal fluctuation with a fixed short-range length scale(activation volume).At long time scale,relaxation is slow due to the emergence of a cooperative long-range length scale determined by the stress fluctuation.The cooperative length scale is proportional to the reciprocal of stress and the amplitude of stress fluctuation is the product of stress and activation volume.Based on this two-step mechanism,we propose a new kinetics equation to capture the stress relaxation effectively,where the short time relaxation is described by an Eyring-like local activation and the long-time relaxation is captured by a cooperative excitation process resorting to an extension from the random first order transition theory.Our equation fits the experimental data well and can serve as a model to guide the related experiments of relaxation processes in crystalline solids.
基金Project supported by the National Natural Science Foundation of China(Grant No.10804089)
文摘An oxide p-n heterojunction composed of Pro.6Ca0.4MnO3 film, with a charge order （CO） transition, and lwt% Nb- doped SrTiO3 substrate is fabricated, and the transport properties of the interface are experimentally studied. The rectifying behavior of the junction, well described by the Newman equation, is observed, indicating that tunneling is the dominant process by which the carriers pass through the interface. Above and below the CO transition temperature, satisfactory linear dependencies of junction resistance on temperature are observed, but the slopes of the two resistance-temperature relations are different. The CO process is believed to be relevant to this difference.
基金financially supported by the National Natural Science Foundations of China(Nos.20874046,21074053 and 51133002)National Basic Research Program of China(Nos.2010CB923303,2012CB821503)Fundamental Research Funds for the Central Universities(No.1095020515)
文摘The crowding agent induced phase transition of amphiphilic block copolymers in solution was explicitly considered. The influence of the size and the volume fraction of the crowding agent on the phase separation of ampbiphilic diblock copolymers is investigated by using self-consistent field theory （SCFT） method. The concentration of the disorder to order transition of the block copolymer decreases when the size of the crowding agent is larger than that of the solvent. The higher volume fraction of the crowding agent will induce the transition of the block copolymer from disorder to order state at a lower concentration. The relation between the size and the volume fraction of the crowding agent is elucidated. When the size of the crowding agent is larger, its volume fraction of the disorder to order transition of the block copolymer will be lower. The conformation of the crowding agent considered as a polymer chain is also studied and compared.
基金This work is supported by the National Science Foundation of China(Grant Nos.11405127 and 11904282).
文摘Using a Monte Carlo simulation and the single histogram reweighting technique,we study the critical behaviors and phase transitions of the Baxter-Wu(BW)model on a two-layer triangular lattice with Ising-type interlayer couplings.Via the finite-size analysis,we obtain the transition temperatures and critical exponents at repulsive and attractive interlayer couplings.The data for the repulsive interlayer coupling suggest continuous transitions,and the critical behaviors are the same as those of the 2D BW model,belonging to the four-state Potts universality class.The reduced energy cumulants and the histograms reveal that attractive coupling leads to weak firstorder phase transitions.The pseudocritical exponents with the existence of the interlayer couplings indicate that the first-order transition is very close to the critical point of the 2D standard BW model.
基金The project supported by National Natural Science Foundation of China under Grant No. 10475113
文摘A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemical potentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe twoflavor normal quark matter. Depending on whether mo/A, the ratio of dynamical quark mass in vacuum and the 3D momentum cutoff in the loop integrals, is less or greater than 0.413, the phase transition will be of the second or first order. A complete phase diagram of u quark chemical potential versus mo is given. With the electrical neutrality constraint, the region where the second order phase transition happens will be wider than the one without electrical neutrality limitation. The results also show that, for the value ofmo/A from QCD phenomenology, the phase transition must be of the first order.
文摘The early 21st century finds great change in international order. China＇s foreign relations have entered a new phase where its driving force is rapidly rising for the emerging countries and new global economic govemance mechanism is gradually established. To follow the trend of the times, China has actively participated in global economic govemance and supply of public goods. China＇ s foreign relations present a new vision, idea and strategy under the leadership of President Xi Jinping. It is a new starting point for China to further integrate itself into the world and open itself wider to the world. China takes an active part to participate in global governance and plays an important role in the issues of economic integration, environmental governance, climate change, nuclear nonproliferation, energy crisis, intemet security and anti-terrorism, especially anti-terrorism. This article explains the performance of international relations in current transition order and tries to tackle prior （and in some ways more intractable） issues and to analyze the internal logics and external environment of impact of multi-polarization on China＇s major power diplomacy with its characteristics in the transition of International order.
基金financially supported by the National Natural Science Foundation of China(Nos.51971001,52005007,and U1560105)the Natural Science Foundation of Anhui Province(No.2008085ME125)。
文摘The ageing hardening mechanism of a newly designed Fe65Cr13Cu3(CoMnMoNiAlTi)19 medium-entropy stainless alloy(ME-SA)with a simple bcc solid solution matrix was studied.This kind of ME-SA possessed a higher ageing hardness of approximately 584 HV and higher compressive stress and corrosion resistance than those of the conventional precipitation hardening stainless steel 17-4 PH(Cr17Ni4Cu4 Nb),which has comparable compressive strain.The well-dispersed B2-ordered phase in the cast state transformed to a D03 crystal structure with a higher ordering degree and reduced the precipitate size after ageing at 500℃,thus promoting a great ageing hardening effect.
文摘The connections between different physical-chemical properties in homologous molecular series are analyzed from the quantum-mechanic and the algebraic theory points of view and are explained by influence of the gage to the quantum electronic continuum. The connection between quantum and macroscopic properties of the substances is confirmed in homologous series of n-alkanes. Linear correlation between the coefficient of magnetization and energy of the highest occupied molecular orbital in homologous series of n-alkanes C2-C10 is established. The connection between diamagnetic and electronic characteristics of n-alkanes with the temperatures of the first order phase transitions （melting point） and other physical-chemical properties were discovered. The nature of interconnection between critical and diamagnetic properties of n-alkanes C2-C10 and results of previous works allow to suppose significant role of the spin interactions in electronic continuum states along the process of the first order phase transitions.
基金Project supported by the Scientific Research Foundation for Bringing Talents of Tianjin University of Science and Technology,China (Grant No.20090426)the National Natural Science Foundation of China (Grant Nos.50571112 and 50731007)+1 种基金the National Basic Research Program of China (Grant No.2006CB601101)the Basic Research Program of the Chinese Academy of Sciences (Grant No.KJCX2-YW-W02s)
文摘Magnetic properties and magnetocaloric effect of compound PrFe12B6 are investigated. The coexistence of hard phase PrFe12B6 and soft phase α-Fe causes interesting phenomena on the curves for the temperature dependence of magnetization. PrFe12B6 experiences a first order phase transition at the Curie temperature 206 K, accompanied by an obvious lattice contraction, which in turn results in a large magnetic entropy change. The Maxwell relation fails to give the correct information about magnetic entropy change due to the first order phase transition nature. The large magnetic entropy changes of PrFe12.3B4.7 obtained from heat capacity method are 11.7 and 16.2 J/kg.K for magnetic field changes of 0-2 T and 0-5 T respectively.
基金Supported by the National Natural Science Foundation of China under Grant No.10905020the China Postdoctoral Science Foundation under Grant Nos.201003245 and 20090460592
文摘We have investigated the quasinormal modes （QNMs） of phantom scalar perturbation in a Reissner Nordstr6m （RN） background. We find that the dependence of Q, NMs on the mass of the field for the phantom perturbation is totally different from that of usual massive perturbation. However, we obtain the same critical value of the overtone number for an angular quantum number from which the mass will begin to have a reverse effect on the real part of QNM frequencies and the perturbation-independent relation between the Q, NMs and the second order thermodynamic phase transition.
文摘A.M.W. Glass and S.H.McCleary have given the 2 transitive representation of the countable free l group F η(1<η≤ω 0 ).In this paper we shall give the highly ordered transitive representation of countable free groups on the rational line Q, which generalizes their results. As applications,we obtain the highly ordered transitive representation for the direct product of countable free groups,and the inverse limit of countable free groups must be an action on the set Q.
文摘Because of. the great needs both for the research of pansystem mathematics andfor the analysis of general things' mechanism, this paper discusses the binary relation,stransitivity confined to multirelation. The so-called g-transitvity- a completelynew concept about transitivity- is introduced and its basic properties are investigated.The study shows that it is not only g-transitivity a generalization of traditionaltransitivity, quasi-transitivity, seml-order, quasi-order and other panorder, but alsoincludes many important concepts such as closeness, convexity, topology, duality as itsspecial cases.
基金Project supported by the National Natural Science Foundation of China(Grant No.11204041)STCSM of China(Grant No.15XD1500200)
文摘In order to study the basic superconductivity properties of R2Pt3Ge5, we synthesized the single crystalline samples by the Pt–Ge self-flux method. R2Pt3Ge5（R = La, Ce） were also grown for a systematic study. Zero-resistivity was observed in both the La-and Pr-based samples below the reported superconducting transition temperatures. However, magnetic susceptibility measurements showed low superconductivity volume fractions in both La2Pt3Ge5 and R2Pt3Ge5（less than2%）. Ce2Pt3Ge5 did not show any signature of superconductivity. From the specific heat measurements, we did not observe a superconducting transition peak in R2Pt3Ge5, suggesting that it is not a bulk superconductor. The magnetic susceptibility and heat capacity measurements revealed two antiferromagnetic（AFM） orders in R2Pt3Ge5 at T（N1）= 4.2 K and T（N2）= 3.5K, as well as a single AFM transition at TN= 3.8 K in Ce2Pt3Ge5.
文摘Andrea Corradini,Giovanni Marini&Matteo Calandra Correction to:npj Computational Materials https://doi.org/10.1038/s41524-025-01614-5,published online 26 May 2025“In this article the wrong figure appeared as Fig.7;the figure should have appeared as shown below.The original article has been corrected.”
基金the Talent Scientific Research Program of College of Physics,Sichuan University(Grant No.1082204112427)Yi-Fu Cai was supported in part by the National Natural Science Foundation of China(NSFC)(Grant Nos.11653002,11961131007,1201101448,11722327,and 11421303)+3 种基金the China Association for Science and Technology-Young Elite Scientist Sponsorship(Grant No.2016QNRC001)the National Youth Talents Program of China,the Fundamental Research Funds for Central Universities,the Chinese Scholarship Council Innovation Talent Funds,and the University of Science and Technology of China(USTC)Fellowship for International Cooperation.Antonino Marciano wishes to acknowledge support by the Shanghai Municipality(Grant No.KBH1512299)the Fudan University(Grant No.JJH151210)NSFC(Grant No.11875113)。
文摘The recent NANOGrav evidence of a common-source stochastic background provides a hint to gravitational waves(GW)radiation from the Early Universe.We show that this result can be interpreted as a GW spectrum produced from first order phase transitions(FOPTs)around a temperature in the keV-MeV window.Such a class of FOPTs at temperatures much below the electroweak scale can be naturally envisaged in several warm dark matter models such as Majoron dark matter.
