If the Planck length is chosen as the natural length scale of the Universe, the Penrose-Carter diagram associated with the classical gravitational collapse of a thin spherical shell of massless matter reveals, beyond ...If the Planck length is chosen as the natural length scale of the Universe, the Penrose-Carter diagram associated with the classical gravitational collapse of a thin spherical shell of massless matter reveals, beyond and in agreement with the claimed non locality of the horizon, a quantum nature of the whole process.展开更多
Haggard and Rovelli delineated an outer radius as to the range of quantum effects, which extends past the Schwartzshield radius. This is defined as 7/3 times the mass of the initial cosmological system. We also have a...Haggard and Rovelli delineated an outer radius as to the range of quantum effects, which extends past the Schwartzshield radius. This is defined as 7/3 times the mass of the initial cosmological system. We also have a range of perturbative effects as delineated by Turok’s article which gives a range of values of for which second order perturbative terms in cosmological evolution may play a role, where we have second order perturbation terms for which . Right afterwards, there are no perturbative behavior and no perturbation if . This is the 2<sup>nd</sup> order term for perturbing term for GW (Gravitational wave) as denoted by , and near the “zero point” of cosmological expansion, and from there we determine the size of the quantum effects, i.e. when they initiate, the relevant initial entropy, so as to determine the radii of initial cosmology, so quantum gravity may initiate its activity, in our toy universe. The criteria of Turok is used to obtain the relevant mass, m, used in the initial radii so that it is 7/3 times the mass of the initial cosmological system. We use the “Criteria of Turok” to delineate the start of quantum gravity effects. Mass m is done via appealing to graviton mass, and that times initial entropy, which is commented upon in Equation (9).展开更多
The research work on the quantum effects in mesoscopic circuits has undergone a rapid development recently, however the whole quantum theory of the mesoscopic circuits should consider the discreteness of the electric ...The research work on the quantum effects in mesoscopic circuits has undergone a rapid development recently, however the whole quantum theory of the mesoscopic circuits should consider the discreteness of the electric charge. In this paper, based on the fundamental fact that the electric charge takes discrete values, the finite-difference Schrodinger equation of.the mesoscopic RLC circuit with a source is achieved. With a unitary transformation, the Schrodinger equation becomes the standard Mathieu equation, then the energy spectrum and the wave functions of the system are obtained. Using the WKBJ method, the average of currents and square of the current are calculated. The results show the existence of the current fluctuation, which causes noise in the circuits. This paper is an application of the whole quantum mesoscopic circuits theory to the fundamental circuits, and the results will shed light on the design of the miniation circuits, especially on the purpose of reducing quantum noise coherent controlling of the mesoscopic quantum states.展开更多
The open electron resonator is a mesoscopic device that has attracted considerable attention due to its remarkable behavior:conductance oscillations.In this paper,using an improved quantum theory to mesoscopic circuit...The open electron resonator is a mesoscopic device that has attracted considerable attention due to its remarkable behavior:conductance oscillations.In this paper,using an improved quantum theory to mesoscopic circuits developed recently by Li and Chen,the mesoscopic electron resonator is quantized based on the fundamental fact that the electric charge takes discrete value.With presentation transformation and unitary transformation,the Schr(?)dinger equation becomes an standard Mathieu equation.Then,the detailed energy spectrum and wave functions in the system are obtained,which will be helpful to the observation of other characters of electron resonator.The average of currents and square of the current are calculated,the results show the existence of the current fluctuation,which causes the noise in the circuits,the influence of inductance to the noise is discussed.With the results achieved,the stability characters of mesoscopic electron resonator are studied firstly,these works would be benefit to the design and control of integrate circuit.展开更多
The mesoscopic nonlinear inductance-capacitance circuit is a typical anharmonic oscillator,due to diodesincluded in the circuit.In this paper,using the advanced quantum theory of mesoscopic circuits,which based on the...The mesoscopic nonlinear inductance-capacitance circuit is a typical anharmonic oscillator,due to diodesincluded in the circuit.In this paper,using the advanced quantum theory of mesoscopic circuits,which based on thefundamental fact that the electric charge takes discrete value,the diode included mesoscopic circuit is firstly studied.Schr(o|¨)dinger equation of the system is a four-order difference equation in (?) rep esentation.Using the extended perturbativemethod,the detail energy spectrum and wave functions are obtained and verified,as an application of the results,thecurrent quantum fluctuation in the ground state is calculated.Diode is a basis component in a circuit,its quantizationwould popularize the quantum theory of mesoscopic circuits.The methods to solve the high order difference equationare helpful to the application of mesoscopic quantum theory.展开更多
The correlation between the Schrödinger equation and the diffusion equation revealed that the relation of material wave is not a hypothesis but an actual one valid in a material regardless of the photon energ...The correlation between the Schrödinger equation and the diffusion equation revealed that the relation of material wave is not a hypothesis but an actual one valid in a material regardless of the photon energy. Using the relations of material wave and uncertain principle, the quantum effect on elementary process of diffusion is discussed. As a result, the diffusivity is obtained as a universal expression applicable to any problem of diffusion phenomena. The Gauss theorem in theory and the Kirkendall effect in experimentation reveal the necessity of the coordinate transformation for a diffusion equation. The mathematical method for solving an interdiffusion problem of many elements system is established. The phase shift of the obtained analytical solution indicates the correlation between the solutions of each diffusion equation expressed by a fixed coordinate system and by a moving coordinate system. Based on the coordinate transformation theory, some unsolved problems of diffusion theory are reasonably solved and also some new important findings are discussed in relation to matters in the existing diffusion theory.展开更多
Valley-polarized quantum anomalous Hall effect(VQAHE), combined nontrivial band topology with valleytronics,is of importance for both fundamental sciences and emerging applications. However, the experimental realizati...Valley-polarized quantum anomalous Hall effect(VQAHE), combined nontrivial band topology with valleytronics,is of importance for both fundamental sciences and emerging applications. However, the experimental realization of this property is challenging. Here, by using first-principles calculations and modal analysis, we predict a mechanism of producing VQAHE in two-dimensional ferromagnetic van der Waals germanene/MnI_(2) heterostructure. This heterostructure exhibits both valley anomalous Hall effect and VQAHE due to the joint effects of magnetic exchange effect and spin–orbital coupling with the aid of anomalous Hall conductance and chiral edge state. Moreover interestingly, through the electrical modulation of ferroelectric polarization state in In_(2)Se_(3), the germanene/Mn I_(2)/In_(2)Se_(3) heterostructure can undergo reversible switching from a semiconductor to a metallic behavior. This work offers a guiding advancement for searching for VQAHE in ferromagnetic van der Waals heterostructures and exploiting energy-efficient devices based on the VQAHE.展开更多
We propose a scheme for realizing the spin direction-dependent quantum anomalous Hall effect(QAHE)driven by spin-orbit couplings(SOC)in two-dimensional(2D)materials.Based on the sp^(3)tight-binding(TB)model,we find th...We propose a scheme for realizing the spin direction-dependent quantum anomalous Hall effect(QAHE)driven by spin-orbit couplings(SOC)in two-dimensional(2D)materials.Based on the sp^(3)tight-binding(TB)model,we find that these systems can exhibit a QAHE with out-of-plane and in-plane magnetization for the weak and strong SOC,respectively,in which the mechanism of quantum transition is mainly driven by the band inversion of p_(x,y)/p_(z)orbitals.As a concrete example,based on first-principles calculations,we realize a real material of monolayer 1T-SnN_(2)/PbN_(2)exhibiting the QAHE with in-plane/out-of-plane magnetization characterized by the nonzero Chern number C and topological edge states.These findings provide useful guidance for the pursuit of a spin direction-dependent QAHE and hence stimulate immediate experimental interest.展开更多
The quantum anomalous Hall effect(QAHE) has special quantum properties that are ideal for possible future spintronic devices. However, the experimental realization is rather challenging due to its low Curie temperatur...The quantum anomalous Hall effect(QAHE) has special quantum properties that are ideal for possible future spintronic devices. However, the experimental realization is rather challenging due to its low Curie temperature and small non-trivial bandgap in two-dimensional(2D) materials. In this paper, we demonstrate through first-principles calculations that monolayer Co2Te material is a promising 2D candidate to realize QAHE in practice. Excitingly, through Monte Carlo simulations, it is found that the Curie temperature of single-layer Co2Te can reach 573 K. The band crossing at the Fermi level in monolayer Co2Te is opened when spin–orbit coupling is considered, which leads to QAHE with a sizable bandgap of Eg= 96 me V, characterized by the non-zero Chern number(C = 1) and a chiral edge state. Therefore, our findings not only enrich the study of quantum anomalous Hall effect, but also broaden the horizons of the spintronics and topological nanoelectronics applications.展开更多
Rashba spin splitting(RSS)and quantum spin Hall effect(QSHE)have attracted enormous interest due to their great significance in the application of spintronics.In this work,we theoretically proposed a new two-dimension...Rashba spin splitting(RSS)and quantum spin Hall effect(QSHE)have attracted enormous interest due to their great significance in the application of spintronics.In this work,we theoretically proposed a new two-dimensional(2D)material H–Pb–F with coexistence of giant RSS and quantum spin Hall effec by using the ab initio calculations.Our results show that H–Pb–F possesses giant RSS(1.21 eV·A)and the RSS can be tuned up to 4.16 e V·A by in-plane biaxial strain,which is a huge value among 2D materials.Furthermore,we also noticed that H–Pb–F is a 2D topological insulator(TI)duo to the strong spin–orbit coupling(SOC)interaction,and the large topological gap is up to 1.35 e V,which is large enough for for the observation of topological edge states at room temperature.The coexistence of giant RSS and quantum spin Hall effect greatly broadens the potential application of H–Pb–F in the field of spintronic devices.展开更多
Using the Landau and symmetric gauges for the vector potential of a constant magnetic field and the quantum problem of a charged particle moving on a flat surface, we show the classical electromagnetic gauge transform...Using the Landau and symmetric gauges for the vector potential of a constant magnetic field and the quantum problem of a charged particle moving on a flat surface, we show the classical electromagnetic gauge transformation does not correspond to a one-dimensional unitary group transformation U(1) of the wave function for the quantum case. In addition, with the re-examination of the relation between the magnetic field B and its vector potential A, we found that, in order to have a consistent formulation of the dynamics of the charged particle with both expressions, we must have that B=∇×A if and only if B≠0.展开更多
A previous study is continued by investigating the Boltzmann equation for particles with quantum effects (BQE). First, the corresponding entropy identity is proved, then if the initial data f(x,v,0) satisfies 0...A previous study is continued by investigating the Boltzmann equation for particles with quantum effects (BQE). First, the corresponding entropy identity is proved, then if the initial data f(x,v,0) satisfies 0≤f(x,v,0)≤CΦ(x,v,0) for a constant 0<C<∞ and function Φ(x,v,t), we prove the existence and uniqueness of spatial decay solutions of the BQE within a given function space B(Φ) using fixed point theory. Moreover, if there is a continuous function F(x,v) which belongs to a function set, then there exists a mild solution f(x,v,t) of the BQE such that f ∞(x,v)= limt→∞f(x+vt,v,t)=F(x,v).展开更多
The strain impact on hole mobility in the GOI tri-gate pFETs is investigated by simulating the strained Ge with quantum confinement from band structure to electro-static distribution as well as the effective mobility....The strain impact on hole mobility in the GOI tri-gate pFETs is investigated by simulating the strained Ge with quantum confinement from band structure to electro-static distribution as well as the effective mobility. Lattice mismatch strain induced by HfO2 warps and reshapes the valence subbands, and reduces the hole effective masses. The maximum value of hole density is observed near the top comers of the channel. The hole density is decreased by the lattice mismatch strain. The phonon scattering rate is degraded by strain, which results in higher hole mobility.展开更多
The Boltzmann equations for Fermi-Dirac particles and Bose-Einstein particles, both in the absence of external force fields, are combined into a more general form called the Boltzmann equation with quantum effects (BQ...The Boltzmann equations for Fermi-Dirac particles and Bose-Einstein particles, both in the absence of external force fields, are combined into a more general form called the Boltzmann equation with quantum effects (BQE). It is assumed that the initial data f(x,v,0) satisfies 0≤f(x,v,0)≤cΦ(x,v,0) for a positive constant c and certain types of control functions Φ(x,v,t). Then within a given function space B(Φ), we prove that f(x+tv,v,t) uniformly converges to f ∞(x,v) in a certain norm where f ∞(x,v)= limt→∞f(x+tv,v,t) and different initial data determines different long time limits.展开更多
A theoretical investigation has been carried out on the propagation of the ion–acoustic(IA) waves in a relativistic degenerate plasma containing relativistic degenerate electron and positron fluids in the presence of...A theoretical investigation has been carried out on the propagation of the ion–acoustic(IA) waves in a relativistic degenerate plasma containing relativistic degenerate electron and positron fluids in the presence of inertial non-relativistic light ion fluid. The Korteweg-de Vries(K-dV), modified K-dV(m K-dV), and mixed m K-dV(mm K-dV) equations are derived by adopting the reductive perturbation method. In order to analyze the basic features(phase speed, amplitude, width,etc.) of the IA solitary waves(SWs), the SWs solutions of the K-dV, m K-dV, and mm K-d V are numerically analyzed. It is found that the degenerate pressure, inclusion of the new phenomena like the Fermi temperatures and quantum mechanical effects(arising due to the quantum diffraction) of both electrons and positrons, number densities, etc., of the plasma species remarkably change the basic characteristics of the IA SWs which are found to be formed either with positive or negative potential. The implication of our results in explaining different nonlinear phenomena in astrophysical compact objects, e.g.,white dwarfs, neutron stars, etc., and laboratory plasmas like intense laser–solid matter interaction experiments, etc., are mentioned.展开更多
In recent years,the study of quantum effects near the event horizon of a black hole(BH)has attracted extensive attention.It has become one of the important methods to explore BH quantum properties using the related pr...In recent years,the study of quantum effects near the event horizon of a black hole(BH)has attracted extensive attention.It has become one of the important methods to explore BH quantum properties using the related properties of a quantum deformed BH.In this work,we study the effect of a quantum deformed BH on the BH shadow in two-dimensional Dilaton gravity.In this model,quantum effects are reflected by the quantum correction parameter m.By calculation,we find that:(1)the shape of the shadow boundary of a rotating BH is determined by the BH spin a,the quantum correction parameter m,and the BH type parameter n;(2)when the spin a=0,the shape of the BH shadow is a perfect circle;when a≠0,the shape is distorted;if the quantum correction parameter m=0,their shapes reduce to the cases of a Schwarzschild BH and Kerr BH,respectively;(3)the degree of distortion of the BH shadow is different for various quantum correction parameters m;with an increase in the parameter m,the boundary of the BH shadow expands;(4)the size of the BH shadow varies greatly with respect to various quantum deformed BHs(n),and the change in BH shadow shape caused by parameter n is similar to that caused by parameter m,which indicates that there is a"degenerate phenomenon"between the two parameters.Because the value of m in actual physics should be very small,the current observations of the event horizon telescope(EHT)cannot distinguish quantum effects from the BH shadow.In future BH shadow measurements,it will be possible to distinguish quantum deformed BHs,which will help to better understand the quantum effects of BHs.展开更多
Terahertz(THz) radiation can be generated due to the instability of THz plasma waves in field-effect transistors(FETs). In this work, we discuss the instability of THz plasma waves in the channel of FETs with spin and...Terahertz(THz) radiation can be generated due to the instability of THz plasma waves in field-effect transistors(FETs). In this work, we discuss the instability of THz plasma waves in the channel of FETs with spin and quantum effects under non-ideal boundary conditions. We obtain a linear dispersion relation by using the hydrodynamic equation, Maxwell equation and spin equation. The influence of source capacitance, drain capacitance, spin effects, quantum effects and channel width on the instability of THz plasma waves under the non-ideal boundary conditions is investigated in great detail. The results of numerical simulation show that the THz plasma wave is unstable when the drain capacitance is smaller than the source capacitance;the oscillation frequency with asymmetric boundary conditions is smaller than that under non-ideal boundary conditions;the instability gain of THz plasma waves becomes lower under non-ideal boundary conditions. This finding provides a new idea for finding efficient THz radiation sources and opens up a new mechanism for the development of THz technology.展开更多
Y-shaped Kekulébond textures in a honeycomb lattice on a graphene-copper superlattice have recently been experimentally revealed.In this paper,the effects of such a bond modulation on the transport coefficients o...Y-shaped Kekulébond textures in a honeycomb lattice on a graphene-copper superlattice have recently been experimentally revealed.In this paper,the effects of such a bond modulation on the transport coefficients of Kekulé-patterned graphene are investigated in the presence of a perpendicular magnetic field.Analytical expressions are derived for the Hall and longitudinal conductivities using the Kubo formula.It is found that the Y-shaped Kekulébond texture lifts the valley degeneracy of all Landau levels except that of the zero mode,leading to additional plateaus in the Hall conductivity accompanied by a split of the corresponding peaks in the longitudinal conductivity.Consequently,the Hall conductivity is quantized as±ne^(2)/h for n=2,4,6,8,10,...,excluding some plateaus that disappear due to the complete overlap of the Landau levels of different cones.These results also suggest that DC Hall conductivity measurements will allow us to determine the Kekulébond texture amplitude.展开更多
文摘If the Planck length is chosen as the natural length scale of the Universe, the Penrose-Carter diagram associated with the classical gravitational collapse of a thin spherical shell of massless matter reveals, beyond and in agreement with the claimed non locality of the horizon, a quantum nature of the whole process.
文摘Haggard and Rovelli delineated an outer radius as to the range of quantum effects, which extends past the Schwartzshield radius. This is defined as 7/3 times the mass of the initial cosmological system. We also have a range of perturbative effects as delineated by Turok’s article which gives a range of values of for which second order perturbative terms in cosmological evolution may play a role, where we have second order perturbation terms for which . Right afterwards, there are no perturbative behavior and no perturbation if . This is the 2<sup>nd</sup> order term for perturbing term for GW (Gravitational wave) as denoted by , and near the “zero point” of cosmological expansion, and from there we determine the size of the quantum effects, i.e. when they initiate, the relevant initial entropy, so as to determine the radii of initial cosmology, so quantum gravity may initiate its activity, in our toy universe. The criteria of Turok is used to obtain the relevant mass, m, used in the initial radii so that it is 7/3 times the mass of the initial cosmological system. We use the “Criteria of Turok” to delineate the start of quantum gravity effects. Mass m is done via appealing to graviton mass, and that times initial entropy, which is commented upon in Equation (9).
基金the National Natural Science Foundation of China under,河北省自然科学基金
文摘The research work on the quantum effects in mesoscopic circuits has undergone a rapid development recently, however the whole quantum theory of the mesoscopic circuits should consider the discreteness of the electric charge. In this paper, based on the fundamental fact that the electric charge takes discrete values, the finite-difference Schrodinger equation of.the mesoscopic RLC circuit with a source is achieved. With a unitary transformation, the Schrodinger equation becomes the standard Mathieu equation, then the energy spectrum and the wave functions of the system are obtained. Using the WKBJ method, the average of currents and square of the current are calculated. The results show the existence of the current fluctuation, which causes noise in the circuits. This paper is an application of the whole quantum mesoscopic circuits theory to the fundamental circuits, and the results will shed light on the design of the miniation circuits, especially on the purpose of reducing quantum noise coherent controlling of the mesoscopic quantum states.
基金The project supported by National Natural Science Foundation of China under Grant No. 10405009 and Natural Science Foundation of Hebei Province of China under Grant No. 103143
基金supported by National Natural Science Foundation of China under Grant No.10405009the Youth Foundation of North China Electric Power University
文摘The open electron resonator is a mesoscopic device that has attracted considerable attention due to its remarkable behavior:conductance oscillations.In this paper,using an improved quantum theory to mesoscopic circuits developed recently by Li and Chen,the mesoscopic electron resonator is quantized based on the fundamental fact that the electric charge takes discrete value.With presentation transformation and unitary transformation,the Schr(?)dinger equation becomes an standard Mathieu equation.Then,the detailed energy spectrum and wave functions in the system are obtained,which will be helpful to the observation of other characters of electron resonator.The average of currents and square of the current are calculated,the results show the existence of the current fluctuation,which causes the noise in the circuits,the influence of inductance to the noise is discussed.With the results achieved,the stability characters of mesoscopic electron resonator are studied firstly,these works would be benefit to the design and control of integrate circuit.
基金Supported by National Natural Science Foundation of China under Grant No.10575028
文摘The mesoscopic nonlinear inductance-capacitance circuit is a typical anharmonic oscillator,due to diodesincluded in the circuit.In this paper,using the advanced quantum theory of mesoscopic circuits,which based on thefundamental fact that the electric charge takes discrete value,the diode included mesoscopic circuit is firstly studied.Schr(o|¨)dinger equation of the system is a four-order difference equation in (?) rep esentation.Using the extended perturbativemethod,the detail energy spectrum and wave functions are obtained and verified,as an application of the results,thecurrent quantum fluctuation in the ground state is calculated.Diode is a basis component in a circuit,its quantizationwould popularize the quantum theory of mesoscopic circuits.The methods to solve the high order difference equationare helpful to the application of mesoscopic quantum theory.
文摘The correlation between the Schrödinger equation and the diffusion equation revealed that the relation of material wave is not a hypothesis but an actual one valid in a material regardless of the photon energy. Using the relations of material wave and uncertain principle, the quantum effect on elementary process of diffusion is discussed. As a result, the diffusivity is obtained as a universal expression applicable to any problem of diffusion phenomena. The Gauss theorem in theory and the Kirkendall effect in experimentation reveal the necessity of the coordinate transformation for a diffusion equation. The mathematical method for solving an interdiffusion problem of many elements system is established. The phase shift of the obtained analytical solution indicates the correlation between the solutions of each diffusion equation expressed by a fixed coordinate system and by a moving coordinate system. Based on the coordinate transformation theory, some unsolved problems of diffusion theory are reasonably solved and also some new important findings are discussed in relation to matters in the existing diffusion theory.
基金Project supported by the National Natural Science Foundation of China (Grant No. 52173283)Taishan Scholar Program of Shandong Province (Grant No. ts20190939)Independent Cultivation Program of Innovation Team of Jinan City (Grant No. 2021GXRC043)。
文摘Valley-polarized quantum anomalous Hall effect(VQAHE), combined nontrivial band topology with valleytronics,is of importance for both fundamental sciences and emerging applications. However, the experimental realization of this property is challenging. Here, by using first-principles calculations and modal analysis, we predict a mechanism of producing VQAHE in two-dimensional ferromagnetic van der Waals germanene/MnI_(2) heterostructure. This heterostructure exhibits both valley anomalous Hall effect and VQAHE due to the joint effects of magnetic exchange effect and spin–orbital coupling with the aid of anomalous Hall conductance and chiral edge state. Moreover interestingly, through the electrical modulation of ferroelectric polarization state in In_(2)Se_(3), the germanene/Mn I_(2)/In_(2)Se_(3) heterostructure can undergo reversible switching from a semiconductor to a metallic behavior. This work offers a guiding advancement for searching for VQAHE in ferromagnetic van der Waals heterostructures and exploiting energy-efficient devices based on the VQAHE.
基金Project supported by Taishan Scholar Program of Shandong Province (Grant No.ts20190939)Independent Cultivation Program of Innovation Team of Jinan City (Grant No.2021GXRC043)the National Natural Science Foundation of China (Grant No.52173283)。
文摘We propose a scheme for realizing the spin direction-dependent quantum anomalous Hall effect(QAHE)driven by spin-orbit couplings(SOC)in two-dimensional(2D)materials.Based on the sp^(3)tight-binding(TB)model,we find that these systems can exhibit a QAHE with out-of-plane and in-plane magnetization for the weak and strong SOC,respectively,in which the mechanism of quantum transition is mainly driven by the band inversion of p_(x,y)/p_(z)orbitals.As a concrete example,based on first-principles calculations,we realize a real material of monolayer 1T-SnN_(2)/PbN_(2)exhibiting the QAHE with in-plane/out-of-plane magnetization characterized by the nonzero Chern number C and topological edge states.These findings provide useful guidance for the pursuit of a spin direction-dependent QAHE and hence stimulate immediate experimental interest.
基金supported by the Taishan Scholar Program of Shandong Province, China (Grant No. ts20190939)the Independent Cultivation Program of Innovation Team of Jinan City (Grant No. 2021GXRC043)the National Natural Science Foundation of China (Grant No. 52173238)。
文摘The quantum anomalous Hall effect(QAHE) has special quantum properties that are ideal for possible future spintronic devices. However, the experimental realization is rather challenging due to its low Curie temperature and small non-trivial bandgap in two-dimensional(2D) materials. In this paper, we demonstrate through first-principles calculations that monolayer Co2Te material is a promising 2D candidate to realize QAHE in practice. Excitingly, through Monte Carlo simulations, it is found that the Curie temperature of single-layer Co2Te can reach 573 K. The band crossing at the Fermi level in monolayer Co2Te is opened when spin–orbit coupling is considered, which leads to QAHE with a sizable bandgap of Eg= 96 me V, characterized by the non-zero Chern number(C = 1) and a chiral edge state. Therefore, our findings not only enrich the study of quantum anomalous Hall effect, but also broaden the horizons of the spintronics and topological nanoelectronics applications.
基金the National Natural Science Foundation of China(Grant Nos.11874316,11404275,and 11474244)the National Basic Research Program of China(Grant No.2015CB921103)+2 种基金the Natural Science Foundation of Hunan Province,China(Grant Nos.2016JJ3118 and 2020JJ4244)the Scientific Research Foundation of the Education Bureau of Hunan Province,China(Grant Nos.16K084,17K086,and 21A049)the Fund for the Innovative Research Team in University(Grant No.IRT13093).
文摘Rashba spin splitting(RSS)and quantum spin Hall effect(QSHE)have attracted enormous interest due to their great significance in the application of spintronics.In this work,we theoretically proposed a new two-dimensional(2D)material H–Pb–F with coexistence of giant RSS and quantum spin Hall effec by using the ab initio calculations.Our results show that H–Pb–F possesses giant RSS(1.21 eV·A)and the RSS can be tuned up to 4.16 e V·A by in-plane biaxial strain,which is a huge value among 2D materials.Furthermore,we also noticed that H–Pb–F is a 2D topological insulator(TI)duo to the strong spin–orbit coupling(SOC)interaction,and the large topological gap is up to 1.35 e V,which is large enough for for the observation of topological edge states at room temperature.The coexistence of giant RSS and quantum spin Hall effect greatly broadens the potential application of H–Pb–F in the field of spintronic devices.
文摘Using the Landau and symmetric gauges for the vector potential of a constant magnetic field and the quantum problem of a charged particle moving on a flat surface, we show the classical electromagnetic gauge transformation does not correspond to a one-dimensional unitary group transformation U(1) of the wave function for the quantum case. In addition, with the re-examination of the relation between the magnetic field B and its vector potential A, we found that, in order to have a consistent formulation of the dynamics of the charged particle with both expressions, we must have that B=∇×A if and only if B≠0.
基金Supported by the Tsinghua U niversity Science Fund
文摘A previous study is continued by investigating the Boltzmann equation for particles with quantum effects (BQE). First, the corresponding entropy identity is proved, then if the initial data f(x,v,0) satisfies 0≤f(x,v,0)≤CΦ(x,v,0) for a constant 0<C<∞ and function Φ(x,v,t), we prove the existence and uniqueness of spatial decay solutions of the BQE within a given function space B(Φ) using fixed point theory. Moreover, if there is a continuous function F(x,v) which belongs to a function set, then there exists a mild solution f(x,v,t) of the BQE such that f ∞(x,v)= limt→∞f(x+vt,v,t)=F(x,v).
文摘The strain impact on hole mobility in the GOI tri-gate pFETs is investigated by simulating the strained Ge with quantum confinement from band structure to electro-static distribution as well as the effective mobility. Lattice mismatch strain induced by HfO2 warps and reshapes the valence subbands, and reduces the hole effective masses. The maximum value of hole density is observed near the top comers of the channel. The hole density is decreased by the lattice mismatch strain. The phonon scattering rate is degraded by strain, which results in higher hole mobility.
基金Supported by the Tsinghua U niversity Science Fund
文摘The Boltzmann equations for Fermi-Dirac particles and Bose-Einstein particles, both in the absence of external force fields, are combined into a more general form called the Boltzmann equation with quantum effects (BQE). It is assumed that the initial data f(x,v,0) satisfies 0≤f(x,v,0)≤cΦ(x,v,0) for a positive constant c and certain types of control functions Φ(x,v,t). Then within a given function space B(Φ), we prove that f(x+tv,v,t) uniformly converges to f ∞(x,v) in a certain norm where f ∞(x,v)= limt→∞f(x+tv,v,t) and different initial data determines different long time limits.
文摘A theoretical investigation has been carried out on the propagation of the ion–acoustic(IA) waves in a relativistic degenerate plasma containing relativistic degenerate electron and positron fluids in the presence of inertial non-relativistic light ion fluid. The Korteweg-de Vries(K-dV), modified K-dV(m K-dV), and mixed m K-dV(mm K-dV) equations are derived by adopting the reductive perturbation method. In order to analyze the basic features(phase speed, amplitude, width,etc.) of the IA solitary waves(SWs), the SWs solutions of the K-dV, m K-dV, and mm K-d V are numerically analyzed. It is found that the degenerate pressure, inclusion of the new phenomena like the Fermi temperatures and quantum mechanical effects(arising due to the quantum diffraction) of both electrons and positrons, number densities, etc., of the plasma species remarkably change the basic characteristics of the IA SWs which are found to be formed either with positive or negative potential. The implication of our results in explaining different nonlinear phenomena in astrophysical compact objects, e.g.,white dwarfs, neutron stars, etc., and laboratory plasmas like intense laser–solid matter interaction experiments, etc., are mentioned.
基金Supported the Special Natural Science Fund of Guizhou University (X2020068)the financial support from the China Postdoctoral Science Foundation Funded Project (2019M650846)。
文摘In recent years,the study of quantum effects near the event horizon of a black hole(BH)has attracted extensive attention.It has become one of the important methods to explore BH quantum properties using the related properties of a quantum deformed BH.In this work,we study the effect of a quantum deformed BH on the BH shadow in two-dimensional Dilaton gravity.In this model,quantum effects are reflected by the quantum correction parameter m.By calculation,we find that:(1)the shape of the shadow boundary of a rotating BH is determined by the BH spin a,the quantum correction parameter m,and the BH type parameter n;(2)when the spin a=0,the shape of the BH shadow is a perfect circle;when a≠0,the shape is distorted;if the quantum correction parameter m=0,their shapes reduce to the cases of a Schwarzschild BH and Kerr BH,respectively;(3)the degree of distortion of the BH shadow is different for various quantum correction parameters m;with an increase in the parameter m,the boundary of the BH shadow expands;(4)the size of the BH shadow varies greatly with respect to various quantum deformed BHs(n),and the change in BH shadow shape caused by parameter n is similar to that caused by parameter m,which indicates that there is a"degenerate phenomenon"between the two parameters.Because the value of m in actual physics should be very small,the current observations of the event horizon telescope(EHT)cannot distinguish quantum effects from the BH shadow.In future BH shadow measurements,it will be possible to distinguish quantum deformed BHs,which will help to better understand the quantum effects of BHs.
基金funded by National Natural Science Foundation of China (No. 12065015)the Hongliu First-level Discipline Construction Project of Lanzhou University of Technology。
文摘Terahertz(THz) radiation can be generated due to the instability of THz plasma waves in field-effect transistors(FETs). In this work, we discuss the instability of THz plasma waves in the channel of FETs with spin and quantum effects under non-ideal boundary conditions. We obtain a linear dispersion relation by using the hydrodynamic equation, Maxwell equation and spin equation. The influence of source capacitance, drain capacitance, spin effects, quantum effects and channel width on the instability of THz plasma waves under the non-ideal boundary conditions is investigated in great detail. The results of numerical simulation show that the THz plasma wave is unstable when the drain capacitance is smaller than the source capacitance;the oscillation frequency with asymmetric boundary conditions is smaller than that under non-ideal boundary conditions;the instability gain of THz plasma waves becomes lower under non-ideal boundary conditions. This finding provides a new idea for finding efficient THz radiation sources and opens up a new mechanism for the development of THz technology.
文摘Y-shaped Kekulébond textures in a honeycomb lattice on a graphene-copper superlattice have recently been experimentally revealed.In this paper,the effects of such a bond modulation on the transport coefficients of Kekulé-patterned graphene are investigated in the presence of a perpendicular magnetic field.Analytical expressions are derived for the Hall and longitudinal conductivities using the Kubo formula.It is found that the Y-shaped Kekulébond texture lifts the valley degeneracy of all Landau levels except that of the zero mode,leading to additional plateaus in the Hall conductivity accompanied by a split of the corresponding peaks in the longitudinal conductivity.Consequently,the Hall conductivity is quantized as±ne^(2)/h for n=2,4,6,8,10,...,excluding some plateaus that disappear due to the complete overlap of the Landau levels of different cones.These results also suggest that DC Hall conductivity measurements will allow us to determine the Kekulébond texture amplitude.