Compared to the well-studied two-dimensional(2D)ferroelectricity,the appearance of 2D antiferroelectricity is much rarer,where local dipoles from the nonequivalent sublattices within 2D monolayers are oppositely orien...Compared to the well-studied two-dimensional(2D)ferroelectricity,the appearance of 2D antiferroelectricity is much rarer,where local dipoles from the nonequivalent sublattices within 2D monolayers are oppositely oriented.Using NbOCl_(2) monolayer with competing ferroelectric(FE)and antiferroelectric(AFE)phases as a 2D material platform,we demonstrate the emergence of intrinsic antiferroelectricity in NbOCl_(2) monolayer under experimentally accessible shear strain,along with new functionality associated with electric field-induced AFE-to-FE phase transition.Specifically,the complex configuration space accommodating FE and AFE phases,polarization switching kinetics,and finite temperature thermodynamic properties of 2D NbOCl_(2) are all accurately predicted by large-scale molecular dynamics simulations based on deep learning interatomic potential model.Moreover,room temperature stable antiferroelectricity with low polarization switching barrier and one-dimensional collinear polarization arrangement is predicted in shear-deformed NbOCl_(2) monolayer.The transition from AFE to FE phase in 2D NbOCl_(2) can be triggered by a low critical electric field,leading to a double polarization–electric(P–E)loop with small hysteresis.A new type of optoelectronic device composed of AFE-NbOCl_(2) is proposed,enabling electric“writing”and nonlinear optical“reading”logical operation with fast operation speed and low power consumption.展开更多
1 Introduction Let L be a lattice and CS(L) be the family of all convex sublattices of L, includingthe empty set.Then CS(L), partially ordered by inclusion, forms an atomic algebraic lat-tice. K. M. Koh investigated s...1 Introduction Let L be a lattice and CS(L) be the family of all convex sublattices of L, includingthe empty set.Then CS(L), partially ordered by inclusion, forms an atomic algebraic lat-tice. K. M. Koh investigated some basic concepts and results of CS(L), and raised the following Problem.展开更多
Taking Au3Cu-type sublattice system as an example, three discoveries have been presented. First, the fourth barrier to hinder the progress of metal materials science is that today’s researchers do not understand that...Taking Au3Cu-type sublattice system as an example, three discoveries have been presented. First, the fourth barrier to hinder the progress of metal materials science is that today’s researchers do not understand that the Gibbs energy function of an alloy phase should be derived from Gibbs energy partition function constructed of alloy gene sequence and their Gibbs energy sequence. Second, the six rules for establishing alloy gene Gibbs energy partition function have been discovered, and it has been specially proved that the probabilities of structure units occupied at the Gibbs energy levels in the degeneracy factor for calculating configuration entropy should be degenerated as ones of component atoms occupied at the lattice points. Third, the main characteristics unexpected by today’s researchers are as follows. There exists a single-phase boundary curve without two-phase region coexisting by the ordered and disordered phases. The composition and temperature of the top point on the phase-boundary curve are far away from those of the critical point of the Au3Cu compound; At 0 K, the composition of the lowest point on the composition-dependent Gibbs energy curve is notably deviated from that of the Au3Cu compounds. The theoretical limit composition range of long range ordered Au3Cu-type alloys is determined by the first jumping order degree.展开更多
Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing exp...Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing experimental phenomena of alloy phase transitions during extremely slow variation in temperature by equilibrium thinking mode and then taking erroneous knowledge of experimental phenomena as selected information for establishing Gibbs energy function and so-called equilibrium phase diagram. Second, the equilibrium holographic network phase diagrams of AuCu3-type sublattice system may be used to describe systematic correlativity of the composition?temperature-dependent alloy gene arranging structures and complete thermodynamic properties, and to be a standard for studying experimental subequilibrium order-disorder transition. Third, the equilibrium transition of each alloy is a homogeneous single-phase rather than a heterogeneous two-phase, and there exists a single-phase boundary curve without two-phase region of the ordered and disordered phases; the composition and temperature of the top point on the phase-boundary curve are far away from the ones of the critical point of the AuCu3 compound.展开更多
Magnetizations of four sublattice bilayer system have been systematically investigated by the use of effectivefield theory with self-spin correlations and differential operator technique. The effects of the crystal fi...Magnetizations of four sublattice bilayer system have been systematically investigated by the use of effectivefield theory with self-spin correlations and differential operator technique. The effects of the crystal field, longitudinal magnetic field, and intra- and inter-monolayer interaction constants on magnetizations axe examined in detail. Some interesting results are obtained, which may potentially be related to experimental work.展开更多
The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman s...The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman spectra,ρ–T curves and MR–T curves of the compounds above were measured.The results show that single phase can be obtained at different Nd substitution ratios,and with the increase in Nd doping,the magnetic structure of the system transforms from long-range ferro-magnetic order to spin cluster glass state and antiferro-magnetic state;and the phase separation appears in the samples with x=0.3 and 0.4.The transport property exhibits variation with the increase in Nd doping,and the electric behavior of the sample transforms(from metal state to insulator–metal transition,and then insulator state)is accompanied by colossal magnetoresistance(CMR)effect,which can be attributed to the different couplings of sublattices induced by Nd doping and the interface tun-neling effect related to the spin.展开更多
Based on the two sublattice model of the regular solution,one being metal atom sublattice and another being interstitial atom sublattice,a thermodynamic model for the precipitates of niobium carbonitride,vanadium carb...Based on the two sublattice model of the regular solution,one being metal atom sublattice and another being interstitial atom sublattice,a thermodynamic model for the precipitates of niobium carbonitride,vanadium carbonitride and titanium carbonitride was established to study the starting-temperature of precipitates and the austenite compositions at given temperature in a low carbon steel.The calculation results show that starting-temperature of the precipitation of niobium carbonitride,vanadium carbonitride and titanium carbonitride are 1100℃,920℃and 1340℃,respectively,the mole fraction of carbonitride precipitates is 8.65×10-4 in the 0.053C-0.0028N-1.28Mn-0.008S-0.031Al-0.046Nb-0.008Ti0.029V-Fe steel.When the N content is from 0.0028%to 0.0056%,the starting-temperature of the precipitation of the titanium carbonitride changes from 1340℃to 1430℃.And the C content is from 0.053%to 0.07%,the startingtemperature of the precipitation of the titanium carbonitride hardly changes,but the atomic fraction of niobium in the carbonitride obviously increases.展开更多
A topological space denoted by Fspec(D),called L-fuzzy prime spectrum of a bounded distributive lattice D is introduced.This space Fspec(D) is compact and it contains a subspace homeomorphic with the prime spectrum of...A topological space denoted by Fspec(D),called L-fuzzy prime spectrum of a bounded distributive lattice D is introduced.This space Fspec(D) is compact and it contains a subspace homeomorphic with the prime spectrum of D which is dense in it.The correspondence associating D to the topological space Fspec(D) is shown to define a contravarient functor from the category of bounded distributive lattices into the category of compact topological spaces.展开更多
We investigate the chiral edge states-induced Josephson current–phase relation in a graphene-based Josephson junction modulated by the off-resonant circularly polarized light and the staggered sublattice potential.By...We investigate the chiral edge states-induced Josephson current–phase relation in a graphene-based Josephson junction modulated by the off-resonant circularly polarized light and the staggered sublattice potential.By solving the Bogoliubov–de Gennes equation,a φ_(0) Josephson junction is induced in the coaction of the off-resonant circularly polarized light and the staggered sublattice potential,which arises from the fact that the center of-mass wave vector of Cooper pair becomes finite and the opposite center of-mass wave vector to compensate is lacking in the nonsuperconducting region.Interestingly,when the direction of polarization of light is changed,-φ_(0) to φ_(0) transition generates,which generalizes the concept of traditional 0–πtransition.Our findings provide a purely optical way to manipulate a phase-controllable Josephson device and guidelines for future experiments to confirm the presence of graphene-based φ_(0)Josephson junction.展开更多
The energy transfer phenomenon of Ce→Gd→Tb via Gd sublattice and its depandence has been investigated in GdxY-1-xP5O14:Ce,Tb.The fluorescent and excitation spectra of Gdp5O14,Gdp5O14:Ce,Gdp5O14:Tb and GdxY-1xP5O14:C...The energy transfer phenomenon of Ce→Gd→Tb via Gd sublattice and its depandence has been investigated in GdxY-1-xP5O14:Ce,Tb.The fluorescent and excitation spectra of Gdp5O14,Gdp5O14:Ce,Gdp5O14:Tb and GdxY-1xP5O14:Ce,Tb and absorption spectrum of Gdp5O14 have been studied.The results show that as x is larger than 0.7.the energy transfer from Ce3+ via Gd3+to Tb3+ is obvious.The main reason for the energy transfer of Ce→Gd→Tb being efficient in the region x>0.7 is that the spectral overlap between Ce3+ emission spectrum and Gd3+ absorption spectrum increases and the structure changes from monoclinic Ⅱ(C2/c) layer structure(x<0.7) to monoclinic I(P21/c) ribbon structure.展开更多
Preparation, structure and spectral properties of rare earth pentaphosphates Gd_xY_(1-x)P_5O_(14): Ce, Tb have been investigated. When x>0. 7, the pentaphosphates belong to monoclinic crystal system Ⅰ with space g...Preparation, structure and spectral properties of rare earth pentaphosphates Gd_xY_(1-x)P_5O_(14): Ce, Tb have been investigated. When x>0. 7, the pentaphosphates belong to monoclinic crystal system Ⅰ with space group P2_1/c (C). When x≤0. 7. they belong to monoclinic crystal system Ⅱ with C2/c (C). The fluorescent and excitation spectra of Gdp_5O_(14), GdP_5O_(14): Ce. GdP_5O_(14) : Tb and Gd_xY_(1-x)P_5O_(14) : Ce, Tb have been studied and the energy transfer phenomenon from Ce(3+)→Gd(3+)→Tb(3+) by the medium of Gd(3+) sublattice has been determined.展开更多
The mixed spin-2 and spin-5/2 Ising ferrimagnetic system with different anisotropies (DA/z|J|) for the spin-2 and (DB/z|J|) for the spin-5/2 is studied by the use of the mean-field theory based on the Bogoliubov inequ...The mixed spin-2 and spin-5/2 Ising ferrimagnetic system with different anisotropies (DA/z|J|) for the spin-2 and (DB/z|J|) for the spin-5/2 is studied by the use of the mean-field theory based on the Bogoliubov inequality for the free energy. First, the ground state phase diagram of the system at zero temperature is obtained on the (DA/z|J|,DB/z|J|) plane. Topologically, different kinds of phase diagrams are achieved by changing the temperature and the values of the single ion anisotropies DA/z|J| and DB/z|J|. Besides second-order transition lines, first order phase transition lines terminating at tricritical points, are found. The existence and dependence of a compensation temperature on single-ion anisotropies is also investigated.展开更多
We present a theoretical study of quantum charge pumping in metallic armchair graphene nanoribbons using the Floquet Green function method. A central part of the ribbon acting as the scattering region is supposed to h...We present a theoretical study of quantum charge pumping in metallic armchair graphene nanoribbons using the Floquet Green function method. A central part of the ribbon acting as the scattering region is supposed to have staggered sublattiee potential to open a finite band gap. A single ae gate is asymmetrically applied to a part of the scattering region to drive the pumping. Corresponding to the gap edges, there are two pumped current peaks with opposite current directions, which can be reversed by changing the position of the ac gate relative to the scattering region. The effects of the parameters, such as the staggered sublattice potential, the driving frequency and the geometric parameters of the structure, on the pumping are discussed.展开更多
While certain magnetic sublattices have long been known theoretically to give rise to emergent physics via competing magnetic interactions and quantum effects,finding such configurations in real materials is often dee...While certain magnetic sublattices have long been known theoretically to give rise to emergent physics via competing magnetic interactions and quantum effects,finding such configurations in real materials is often deeply challenging.Here we report the synthesis and characterization of a new such material,NaCo_(2)(SeO_(3))_(2)(OH)which crystallizes with a highly frustrated sublattice of sawtooth Co2+chains.展开更多
Sublattice dichotomy in monolayer FeSe/SrTiO_(3),signaling the breaking of symmetries exchanging the two Fe sublattices,has recently been reported.We propose that interband pairing serves as the origin of this dichoto...Sublattice dichotomy in monolayer FeSe/SrTiO_(3),signaling the breaking of symmetries exchanging the two Fe sublattices,has recently been reported.We propose that interband pairing serves as the origin of this dichotomy,regardless of whether the symmetries are broken in the normal state or in the pairing state.If symmetry breaking occurs in the normal state,the Fermi surfaces are sublattice-polarized,and the intersublattice d-wave pairing naturally acts as interband pairing,reproducing the observed dichotomy in the spectra.Alternatively,if symmetry breaking takes place in the pairing state,the dichotomy arises from the coexistence of intraband and interband pairing,with the constraint that interband pairings share the same sign while intraband pairings carry opposite signs.In both cases,interband pairing is indispensable,establishing it as a key ingredient for understanding superconductivity in monolayer FeSe/SrTiO_(3).展开更多
A brief description of the thermal,structural and dielectric properties of bis(ethylammonium)pentachlorobismuthate(III)ferroelectric with Ps that equals to 1.4μC cm^(-2)at 180 K is presented.This paper focuses in par...A brief description of the thermal,structural and dielectric properties of bis(ethylammonium)pentachlorobismuthate(III)ferroelectric with Ps that equals to 1.4μC cm^(-2)at 180 K is presented.This paper focuses in particular on the molecular mechanism of a phase transition that is related mainly to the deformation of the anionic sublattice confirmed by temperature-variable powdered UV-Vis spectroscopy.展开更多
As early as 1968,metallic hydrogen was considered a potential room-temperature superconductor within the frame of conventional theory for superconductivity[1].However,the metallization of elemental hydrogen needs extr...As early as 1968,metallic hydrogen was considered a potential room-temperature superconductor within the frame of conventional theory for superconductivity[1].However,the metallization of elemental hydrogen needs extremely high pressure as a prerequisite,which is also a holy grail in high-pressure physics.In 2004,Ashcroft[2]proposed that the introduction of other chemical elements can stabilize the sublattice of metallic hydrogen at lower pressures,which is referred to as“chemical precompression”.展开更多
Geometrically frustrated magnetic materials provide an important platform for studying emergent quantum magnetism.Materials that host a triangular or Kagome magnetic sublattice have been intensively studied within thi...Geometrically frustrated magnetic materials provide an important platform for studying emergent quantum magnetism.Materials that host a triangular or Kagome magnetic sublattice have been intensively studied within this realm of research.Here,we point out that more lattice types can be considered geometrically frustrated since a single triangular motif is sufficient to introduce geometrical frustration.Archimedean lattices present uniform tiling in space.In addition to triangular and Kagome lattices,Archimedean lattices include maple-leaf(ML),Shastry-Sutherland(SS),trellis,ruby,and star lattices that are all triangle containing.Through a systematic search of the literature and known inorganic crystal structure databases(ICSDs),we identify materials that realize these less-common lattice types,offering new opportunities to study frustrated magnetism in diverse settings.展开更多
Discovering new materials with desirable band gap and gap state is a central task in the semiconductor community,primarily relying on composition modulation.In this work,by employing atomic simulations,using transitio...Discovering new materials with desirable band gap and gap state is a central task in the semiconductor community,primarily relying on composition modulation.In this work,by employing atomic simulations,using transition-metal dichalcogenide Re_(0.5)Nb_(0.5)(S_(0.5)X_(0.5))_(2)(X=Se,Te)monolayer as an example,we present an alternative avenue for gap state engineering via leveraging diverse chemical short-range orders(SROs).It is found the electronic state contributed by the SRO motif tends to be occupied and may merge with the valence band,yielding a clean band gap in these multicomponent systems.On the contrary,the energy unfavorable local configurations,can produce localized states.The chemical environment in the chalcogen sublattice which has negligible influence on the band gap size can further fine-tune the gap states.The strong coupling of multiple short-range orders and gap states revealed in our work unlock the potential application of a vast family of multicomponent semiconductors.展开更多
Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we sum...Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we summarize the recent research progress on this large family compounds covering diamond-like chalcogenides and liquid-like Cu2X (X=S,Se,Te)binary compounds as well as their multinary derivatives.These materials have the general features of two sublattices to decouple electron and phonon transport properties.On the one hand,the complex crystal structure and the disordered or even liquid-like sublattice bring about an intrinsically low lattice thermal conductivity.On the other hand, the rigid sublattice constitutes the charge-transport network, maintaining a decent electrical performance.For specific material systems,we demonstrate their unique structural features and outline the structure-performance correlation. Various design strategies including doping,alloying,band engineering and nanostructure architecture,covering nearly all the material scale,are also presented.Finally,the potential of the application of Cu-based chalcogenides as high-performance thermoelectric materials is briefly discussed from material design to device development.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.11574244 for G.Y.G.)the XJTU Research Fund for AI Science (Grant No.2025YXYC011 for G.Y.G.)the Hong Kong Global STEM Professorship Scheme (for X.C.Z.)。
文摘Compared to the well-studied two-dimensional(2D)ferroelectricity,the appearance of 2D antiferroelectricity is much rarer,where local dipoles from the nonequivalent sublattices within 2D monolayers are oppositely oriented.Using NbOCl_(2) monolayer with competing ferroelectric(FE)and antiferroelectric(AFE)phases as a 2D material platform,we demonstrate the emergence of intrinsic antiferroelectricity in NbOCl_(2) monolayer under experimentally accessible shear strain,along with new functionality associated with electric field-induced AFE-to-FE phase transition.Specifically,the complex configuration space accommodating FE and AFE phases,polarization switching kinetics,and finite temperature thermodynamic properties of 2D NbOCl_(2) are all accurately predicted by large-scale molecular dynamics simulations based on deep learning interatomic potential model.Moreover,room temperature stable antiferroelectricity with low polarization switching barrier and one-dimensional collinear polarization arrangement is predicted in shear-deformed NbOCl_(2) monolayer.The transition from AFE to FE phase in 2D NbOCl_(2) can be triggered by a low critical electric field,leading to a double polarization–electric(P–E)loop with small hysteresis.A new type of optoelectronic device composed of AFE-NbOCl_(2) is proposed,enabling electric“writing”and nonlinear optical“reading”logical operation with fast operation speed and low power consumption.
文摘1 Introduction Let L be a lattice and CS(L) be the family of all convex sublattices of L, includingthe empty set.Then CS(L), partially ordered by inclusion, forms an atomic algebraic lat-tice. K. M. Koh investigated some basic concepts and results of CS(L), and raised the following Problem.
基金Project(51071181)supported by the National Natural Science Foundation of ChinaProject(2013FJ4043)supported by the Natural Science Foundation of Hunan Province,China
文摘Taking Au3Cu-type sublattice system as an example, three discoveries have been presented. First, the fourth barrier to hinder the progress of metal materials science is that today’s researchers do not understand that the Gibbs energy function of an alloy phase should be derived from Gibbs energy partition function constructed of alloy gene sequence and their Gibbs energy sequence. Second, the six rules for establishing alloy gene Gibbs energy partition function have been discovered, and it has been specially proved that the probabilities of structure units occupied at the Gibbs energy levels in the degeneracy factor for calculating configuration entropy should be degenerated as ones of component atoms occupied at the lattice points. Third, the main characteristics unexpected by today’s researchers are as follows. There exists a single-phase boundary curve without two-phase region coexisting by the ordered and disordered phases. The composition and temperature of the top point on the phase-boundary curve are far away from those of the critical point of the Au3Cu compound; At 0 K, the composition of the lowest point on the composition-dependent Gibbs energy curve is notably deviated from that of the Au3Cu compounds. The theoretical limit composition range of long range ordered Au3Cu-type alloys is determined by the first jumping order degree.
基金Project(51071181)supported by the National Natural Science Foundation of ChinaProject(2013FJ4043)supported by the Natural Science Foundation of Hunan Province,China
文摘Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing experimental phenomena of alloy phase transitions during extremely slow variation in temperature by equilibrium thinking mode and then taking erroneous knowledge of experimental phenomena as selected information for establishing Gibbs energy function and so-called equilibrium phase diagram. Second, the equilibrium holographic network phase diagrams of AuCu3-type sublattice system may be used to describe systematic correlativity of the composition?temperature-dependent alloy gene arranging structures and complete thermodynamic properties, and to be a standard for studying experimental subequilibrium order-disorder transition. Third, the equilibrium transition of each alloy is a homogeneous single-phase rather than a heterogeneous two-phase, and there exists a single-phase boundary curve without two-phase region of the ordered and disordered phases; the composition and temperature of the top point on the phase-boundary curve are far away from the ones of the critical point of the AuCu3 compound.
基金The project supported by the Natural Science Foundation of Liaoning Province under Grant No.20041021the Scientific Foundation of the Educational Department of Liaoning Province under Grant Nos.2004C006 and 20060638the Postdoctoral Foundation of Shenyang University of Technology
文摘Magnetizations of four sublattice bilayer system have been systematically investigated by the use of effectivefield theory with self-spin correlations and differential operator technique. The effects of the crystal field, longitudinal magnetic field, and intra- and inter-monolayer interaction constants on magnetizations axe examined in detail. Some interesting results are obtained, which may potentially be related to experimental work.
基金the Key Programme of Grand Basic Research Programme of China(No.2007CB925001)the National Key Basic Research Programme of China(No.001CB610604)+1 种基金the Grand Natural Science Research Programme of Anhui Education Department(Nos.ZD2007003-1 and KJ2010A074)the Anhui Provincial Natural Science Foundation(No.1308085MA11)。
文摘The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman spectra,ρ–T curves and MR–T curves of the compounds above were measured.The results show that single phase can be obtained at different Nd substitution ratios,and with the increase in Nd doping,the magnetic structure of the system transforms from long-range ferro-magnetic order to spin cluster glass state and antiferro-magnetic state;and the phase separation appears in the samples with x=0.3 and 0.4.The transport property exhibits variation with the increase in Nd doping,and the electric behavior of the sample transforms(from metal state to insulator–metal transition,and then insulator state)is accompanied by colossal magnetoresistance(CMR)effect,which can be attributed to the different couplings of sublattices induced by Nd doping and the interface tun-neling effect related to the spin.
基金the National Natural Science Foundation of China(No.50901022,51071019 and 50271009)the Vanadium International Technical Committee
文摘Based on the two sublattice model of the regular solution,one being metal atom sublattice and another being interstitial atom sublattice,a thermodynamic model for the precipitates of niobium carbonitride,vanadium carbonitride and titanium carbonitride was established to study the starting-temperature of precipitates and the austenite compositions at given temperature in a low carbon steel.The calculation results show that starting-temperature of the precipitation of niobium carbonitride,vanadium carbonitride and titanium carbonitride are 1100℃,920℃and 1340℃,respectively,the mole fraction of carbonitride precipitates is 8.65×10-4 in the 0.053C-0.0028N-1.28Mn-0.008S-0.031Al-0.046Nb-0.008Ti0.029V-Fe steel.When the N content is from 0.0028%to 0.0056%,the starting-temperature of the precipitation of the titanium carbonitride changes from 1340℃to 1430℃.And the C content is from 0.053%to 0.07%,the startingtemperature of the precipitation of the titanium carbonitride hardly changes,but the atomic fraction of niobium in the carbonitride obviously increases.
基金UGC,New Delhi for financial support through scheme F.No33-109/2007(SR)
文摘A topological space denoted by Fspec(D),called L-fuzzy prime spectrum of a bounded distributive lattice D is introduced.This space Fspec(D) is compact and it contains a subspace homeomorphic with the prime spectrum of D which is dense in it.The correspondence associating D to the topological space Fspec(D) is shown to define a contravarient functor from the category of bounded distributive lattices into the category of compact topological spaces.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12104232,11805103,and 11804167)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20190137 and BK20180739)+2 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.020414380195 and B230201042)the Jit-b Project(Grant No.201831)the Natural Science Fund of Nanjing University of Posts and Telecommunications(Grant No.NY222163)。
文摘We investigate the chiral edge states-induced Josephson current–phase relation in a graphene-based Josephson junction modulated by the off-resonant circularly polarized light and the staggered sublattice potential.By solving the Bogoliubov–de Gennes equation,a φ_(0) Josephson junction is induced in the coaction of the off-resonant circularly polarized light and the staggered sublattice potential,which arises from the fact that the center of-mass wave vector of Cooper pair becomes finite and the opposite center of-mass wave vector to compensate is lacking in the nonsuperconducting region.Interestingly,when the direction of polarization of light is changed,-φ_(0) to φ_(0) transition generates,which generalizes the concept of traditional 0–πtransition.Our findings provide a purely optical way to manipulate a phase-controllable Josephson device and guidelines for future experiments to confirm the presence of graphene-based φ_(0)Josephson junction.
文摘The energy transfer phenomenon of Ce→Gd→Tb via Gd sublattice and its depandence has been investigated in GdxY-1-xP5O14:Ce,Tb.The fluorescent and excitation spectra of Gdp5O14,Gdp5O14:Ce,Gdp5O14:Tb and GdxY-1xP5O14:Ce,Tb and absorption spectrum of Gdp5O14 have been studied.The results show that as x is larger than 0.7.the energy transfer from Ce3+ via Gd3+to Tb3+ is obvious.The main reason for the energy transfer of Ce→Gd→Tb being efficient in the region x>0.7 is that the spectral overlap between Ce3+ emission spectrum and Gd3+ absorption spectrum increases and the structure changes from monoclinic Ⅱ(C2/c) layer structure(x<0.7) to monoclinic I(P21/c) ribbon structure.
文摘Preparation, structure and spectral properties of rare earth pentaphosphates Gd_xY_(1-x)P_5O_(14): Ce, Tb have been investigated. When x>0. 7, the pentaphosphates belong to monoclinic crystal system Ⅰ with space group P2_1/c (C). When x≤0. 7. they belong to monoclinic crystal system Ⅱ with C2/c (C). The fluorescent and excitation spectra of Gdp_5O_(14), GdP_5O_(14): Ce. GdP_5O_(14) : Tb and Gd_xY_(1-x)P_5O_(14) : Ce, Tb have been studied and the energy transfer phenomenon from Ce(3+)→Gd(3+)→Tb(3+) by the medium of Gd(3+) sublattice has been determined.
文摘The mixed spin-2 and spin-5/2 Ising ferrimagnetic system with different anisotropies (DA/z|J|) for the spin-2 and (DB/z|J|) for the spin-5/2 is studied by the use of the mean-field theory based on the Bogoliubov inequality for the free energy. First, the ground state phase diagram of the system at zero temperature is obtained on the (DA/z|J|,DB/z|J|) plane. Topologically, different kinds of phase diagrams are achieved by changing the temperature and the values of the single ion anisotropies DA/z|J| and DB/z|J|. Besides second-order transition lines, first order phase transition lines terminating at tricritical points, are found. The existence and dependence of a compensation temperature on single-ion anisotropies is also investigated.
基金Supported by the K.C.Wong Magna Fund in Ningbo Universitythe National Natural Science Foundation of China under Grant No 11474174
文摘We present a theoretical study of quantum charge pumping in metallic armchair graphene nanoribbons using the Floquet Green function method. A central part of the ribbon acting as the scattering region is supposed to have staggered sublattiee potential to open a finite band gap. A single ae gate is asymmetrically applied to a part of the scattering region to drive the pumping. Corresponding to the gap edges, there are two pumped current peaks with opposite current directions, which can be reversed by changing the position of the ac gate relative to the scattering region. The effects of the parameters, such as the staggered sublattice potential, the driving frequency and the geometric parameters of the structure, on the pumping are discussed.
基金supported in part by a University of Missouri Research Council Grant(Grant Number:URC-22-021).The research at the Oak Ridge National Laboratory(ORNL)is supported by the U.S.Department of Energy(DOE),Office of Science,Basic Energy Sciences(BES),Materials Sciences and Engineering Division.This research used resources at the High Flux Isotope Reactor and Spallation Neutron Source,DOE Office of Science User Facilities operated by ORNL.
文摘While certain magnetic sublattices have long been known theoretically to give rise to emergent physics via competing magnetic interactions and quantum effects,finding such configurations in real materials is often deeply challenging.Here we report the synthesis and characterization of a new such material,NaCo_(2)(SeO_(3))_(2)(OH)which crystallizes with a highly frustrated sublattice of sawtooth Co2+chains.
基金supported by the Ministry of Science and Technology(Grant No.2022YFA1403900)the National Natural Science Foundation of China(Grant Nos.12494594,12174428,and 12304163)+2 种基金the New Cornerstone Investigator Programthe Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.2022YSBR-048)the Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Sublattice dichotomy in monolayer FeSe/SrTiO_(3),signaling the breaking of symmetries exchanging the two Fe sublattices,has recently been reported.We propose that interband pairing serves as the origin of this dichotomy,regardless of whether the symmetries are broken in the normal state or in the pairing state.If symmetry breaking occurs in the normal state,the Fermi surfaces are sublattice-polarized,and the intersublattice d-wave pairing naturally acts as interband pairing,reproducing the observed dichotomy in the spectra.Alternatively,if symmetry breaking takes place in the pairing state,the dichotomy arises from the coexistence of intraband and interband pairing,with the constraint that interband pairings share the same sign while intraband pairings carry opposite signs.In both cases,interband pairing is indispensable,establishing it as a key ingredient for understanding superconductivity in monolayer FeSe/SrTiO_(3).
基金supported by the National Science Centregrant no.2013/11/D/ST8/03297(A.Piecha-Bisiorek).
文摘A brief description of the thermal,structural and dielectric properties of bis(ethylammonium)pentachlorobismuthate(III)ferroelectric with Ps that equals to 1.4μC cm^(-2)at 180 K is presented.This paper focuses in particular on the molecular mechanism of a phase transition that is related mainly to the deformation of the anionic sublattice confirmed by temperature-variable powdered UV-Vis spectroscopy.
文摘As early as 1968,metallic hydrogen was considered a potential room-temperature superconductor within the frame of conventional theory for superconductivity[1].However,the metallization of elemental hydrogen needs extremely high pressure as a prerequisite,which is also a holy grail in high-pressure physics.In 2004,Ashcroft[2]proposed that the introduction of other chemical elements can stabilize the sublattice of metallic hydrogen at lower pressures,which is referred to as“chemical precompression”.
基金supported by the US Department of Energy(DOE),Office of Science,Basic Energy Sciences(BES),under award DE-SC0025301B.R.B,acknowledges support from the National Science Foundation under award DGE-2137419S.G.,J.W.,and Z.Q.acknowledge the financial support from the National Natural Science Foundation of China(22205091).
文摘Geometrically frustrated magnetic materials provide an important platform for studying emergent quantum magnetism.Materials that host a triangular or Kagome magnetic sublattice have been intensively studied within this realm of research.Here,we point out that more lattice types can be considered geometrically frustrated since a single triangular motif is sufficient to introduce geometrical frustration.Archimedean lattices present uniform tiling in space.In addition to triangular and Kagome lattices,Archimedean lattices include maple-leaf(ML),Shastry-Sutherland(SS),trellis,ruby,and star lattices that are all triangle containing.Through a systematic search of the literature and known inorganic crystal structure databases(ICSDs),we identify materials that realize these less-common lattice types,offering new opportunities to study frustrated magnetism in diverse settings.
基金supported by the National KeyR&D Program of China(2022ZD0117601)Beijing Natural Science Foundation(Z210018)National Natural Science Foundation of China(No.52173216).
文摘Discovering new materials with desirable band gap and gap state is a central task in the semiconductor community,primarily relying on composition modulation.In this work,by employing atomic simulations,using transition-metal dichalcogenide Re_(0.5)Nb_(0.5)(S_(0.5)X_(0.5))_(2)(X=Se,Te)monolayer as an example,we present an alternative avenue for gap state engineering via leveraging diverse chemical short-range orders(SROs).It is found the electronic state contributed by the SRO motif tends to be occupied and may merge with the valence band,yielding a clean band gap in these multicomponent systems.On the contrary,the energy unfavorable local configurations,can produce localized states.The chemical environment in the chalcogen sublattice which has negligible influence on the band gap size can further fine-tune the gap states.The strong coupling of multiple short-range orders and gap states revealed in our work unlock the potential application of a vast family of multicomponent semiconductors.
基金supported by the National Key Research and Development Program of China (2018YFB0703600)the National Natural Science Foundation of China (51625205)+3 种基金 the Key Research Program of Chinese Academy of Sciences (KFZD-SW-421)Program of Shanghai Subject Chief Scientist (16XD1403900)Youth Innovation Promotion Association, CAS (2016232)Shanghai Sailing Program (18YF1426700).
文摘Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we summarize the recent research progress on this large family compounds covering diamond-like chalcogenides and liquid-like Cu2X (X=S,Se,Te)binary compounds as well as their multinary derivatives.These materials have the general features of two sublattices to decouple electron and phonon transport properties.On the one hand,the complex crystal structure and the disordered or even liquid-like sublattice bring about an intrinsically low lattice thermal conductivity.On the other hand, the rigid sublattice constitutes the charge-transport network, maintaining a decent electrical performance.For specific material systems,we demonstrate their unique structural features and outline the structure-performance correlation. Various design strategies including doping,alloying,band engineering and nanostructure architecture,covering nearly all the material scale,are also presented.Finally,the potential of the application of Cu-based chalcogenides as high-performance thermoelectric materials is briefly discussed from material design to device development.
