By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-...By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-polyacetylene.The dynamical simulation is performed by adopting the non-adiabatic evolution approach.The results show that under the effect of moderate electric field,when the strength of electron-electron interaction is weak,the singlet exciton is stable but its polarization presents obvious oscillation.With the enhancement of interaction,it is dissociated into polaron pairs,the spin-flip of which can be observed through modulating the interaction strength.For the triplet exciton,the strong electron-electron interaction restrains its normal polarization,but it is still stable.In the case of biexciton,the strong electron-electron interaction not only dissociate it,but also flip its charge distribution.The yield of the possible states formed after the dissociation of exciton and biexciton is also calculated.展开更多
We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used ...We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-J model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response theory.An unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this state.The superconducting state with only spin-singlet pairs is dominant with paramagnetic phase.The A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a supercurrent.We also show the superfluid behavior of the unconventional superconducting state and its critical temperature.It is proven directly that the flat band can effectively raise the critical temperature of superconductivity.It is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial structures.Our results may help the understanding of the interplay between unconventional superconductivity and magnetism.展开更多
For an electron-electron collision with characteristic scale length larger than the relative gyro-radius of the two colliding electrons, when the initial relative parallel kinetic energy cannot surmount the Coulomb re...For an electron-electron collision with characteristic scale length larger than the relative gyro-radius of the two colliding electrons, when the initial relative parallel kinetic energy cannot surmount the Coulomb repulsive potential, reflection will occur with interchange of the parallel velocities of the two electrons after the collision. The Fokker–Planck approach is employed to derive the electron collision term C_R describing parallel velocity scattering due to the reflections for a magnetized plasma where the average electron gyro-radius is much smaller than the Debye length but much larger than the Landau length. The electron parallel velocity friction and diffusion coefficients due to the reflections are evaluated, which are found not to depend on the electron perpendicular velocity. By studying the temporal evolution of the H quantity due to CR, it is found that C_R eventually makes the system relax to a state in which the electron parallel velocity distribution is decoupled from the perpendicular velocity distribution.展开更多
We have studied the far-infrared spectra of two-electron vertically coupled quantum dots in an axial magnetic field by exact diagonalization. The calculated results show an obvious difference in role between the inter...We have studied the far-infrared spectra of two-electron vertically coupled quantum dots in an axial magnetic field by exact diagonalization. The calculated results show an obvious difference in role between the interactions for spin S = 1 and for spin S = O. The results support the possibility to evaluate the interactions by far-infrared spectroscopy in vertically coupled quantum dots.展开更多
The three-dimensional electron-electron correlation in an elliptically polarized laser field is investigated based on a semiclassical model. Asymmetry parameter α of the correlated electron momentum distribution is u...The three-dimensional electron-electron correlation in an elliptically polarized laser field is investigated based on a semiclassical model. Asymmetry parameter α of the correlated electron momentum distribution is used to quantitatively describe the electron-electron correlation. The dependence of α on elliptieity e is totally different in three directions. For the z direction (maJor polarization direction), α first increases and reaches a maximum at ε = 0.275, then it decreases quickly. For the y direction in which the laser field is always absent, the ellipticity has a minor effect, and the asymmetry parameter fluctuates around α = -0.15. However, for the x direction (minor polarization direction), α increases monotonously with ellipticity though starts from the same value as in the y direction when ε = 0. The behavior of α in the x direction actually indicates a transformation from the Coulomb interaction dominated correlation to the laser field dominated correlation. Therefore, our work provides an efficient way to control the three-dimensional electron electron correlation via an elliptically polarized intense laser field.展开更多
It is shown that the linear resistivity dependence on temperature for metals above the Debye’s temperature mainly is caused by electron-electron scattering of randomly moving electrons. The electron mean free path in...It is shown that the linear resistivity dependence on temperature for metals above the Debye’s temperature mainly is caused by electron-electron scattering of randomly moving electrons. The electron mean free path in metals at this temperature range is in inverse proportion to the effective density of randomly moving electrons, i.e. it is in inverse proportion both to the temperature, and to the density-of-states at the Fermi surface. The general relationships for estimation of the average diffusion coefficient, the average velocity, mean free length and average relaxation time of randomly moving electrons at the Fermi surface at temperatures above the Debye’s temperature are presented. The effective electron scattering cross-sections for different metals also are estimated. The calculation results of resistivity dependence on temperature in the range of temperature from 1 K to 900 K for Au, Cu, Mo, and Al also are presented and compared with the experimental data. Additionally in temperature range from 1 K to 900 K for copper, the temperature dependences of the mean free path, average diffusion coefficient, average drift mobility, average Hall mobility, average relaxation time of randomly moving electrons, and their resultant phonon mediated scattering cross-section are presented.展开更多
By using a multi-configurational time-dependent Hartree-Fock (MCTDHF) method for the time-dependent Schrrdinger equation and a Newtonian equation of motion for lattice, we investigate the disorder effects on the dis...By using a multi-configurational time-dependent Hartree-Fock (MCTDHF) method for the time-dependent Schrrdinger equation and a Newtonian equation of motion for lattice, we investigate the disorder effects on the dissociation process of excitons in conjugated polymer chains. The simulations are performed within the framework of an extended version of the Su-Schrieffer-Heeger model modified to include on-site disorder, off-diagonal, electron-electron interaction, and an external electric field. Our results show that Coulomb correlation effects play an important role in determining the exciton dissociation process. The electric field required to dissociate an exciton can practically impossibly occur in a pure polymer chain, especially in the case of triplet exciton. However, when the on-site disorder effects are taken into account, this leads to a reduction in mean dissociation electric fields. As the disorder strength increases, the dissociation field decreases effectively. On the contrary, the effects of off-diagonal disorder are negative in most cases. Moreover, the dependence of exciton dissociation on the conjugated length is also discussed.展开更多
By using the exact diagonalization method,a system of three electrons confined in a parabolic quantumdot in zero magnetic field is studied.The ground-state electronic structures and orbital and spin angular momentatra...By using the exact diagonalization method,a system of three electrons confined in a parabolic quantumdot in zero magnetic field is studied.The ground-state electronic structures and orbital and spin angular momentatransitions as a function of the confined strength are investigated.We find that the confinement may cause accidentaldegeneracies between levels with different low-lying states and the inversion of the energy values.The present,resultsare useful to understanding the optical properties and internal electron-electron correlations of quantum dot materials.展开更多
We grew single crystals of vanadium-substituted,ferromagnetic Weyl semimetal candidate Zr1-xVxCo1.6Sn from molten tin flux.These solid solutions all crystallize in a full Heusler structure(L21)while their Curie temper...We grew single crystals of vanadium-substituted,ferromagnetic Weyl semimetal candidate Zr1-xVxCo1.6Sn from molten tin flux.These solid solutions all crystallize in a full Heusler structure(L21)while their Curie temperatures and magnetic moments are enhanced by V-substitution.Their resistivity gradually changes from bad-metal-like to semiconductor-like with increasing x while the anomalous Hall effect(AHE),which can be well fitted by Tian-Ye-Jin(TYJ)scaling,[1]is also enhanced.Moreover,we find an apparent electron-electron interaction(EEI)induced quantum correction in resistivity at low temperature.The anomalous Hall conductivity(AHC)dominated by the intrinsic term is not corrected.展开更多
Based on relativistic multichannel theory, this paper calculates the energy levels of autoionization Rydberg series 4s^2nf(n=4- 23)J^π -(7/2)° of scandium at different levels of approximation within the fram...Based on relativistic multichannel theory, this paper calculates the energy levels of autoionization Rydberg series 4s^2nf(n=4- 23)J^π -(7/2)° of scandium at different levels of approximation within the framework of multichannel quantum defect theory. The present results show that the dipole polarizations play an important role. Considering the dynamical dipole polarization effects, this paper finds that the difference between calculated and experimental quantum defects for the 4s^2nf(n=4- 23)J^π -(7/2)° series is generally about 0.01- 0.03. Furthermore, the reason that 4s^216f is obscured in experimental spectra is suggested to be the interaction with the neighbouring resonance state converged to 3d^2(^1G4) of Sc^+.展开更多
This paper studies the two-electron total energy and the energy of the electron-electron interaction by using a variational method of Pekar type on the condition of electric-LO-phonon strong coupling in a parabolic qu...This paper studies the two-electron total energy and the energy of the electron-electron interaction by using a variational method of Pekar type on the condition of electric-LO-phonon strong coupling in a parabolic quantum dot. It considers the following three cases: 1) two electrons are in the ground state; 2) one electron is in the ground state, the other is in the first-excited state; 3) two electrons are in the first-excited state. The relations of the two-electron total energy and the energy of the electron-electron interaction on the Coulomb binding parameter, the electron-LO-phonon coupling constant and the confinement length of the quantum dot are derived in the three cases.展开更多
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2020MA070).
文摘By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-polyacetylene.The dynamical simulation is performed by adopting the non-adiabatic evolution approach.The results show that under the effect of moderate electric field,when the strength of electron-electron interaction is weak,the singlet exciton is stable but its polarization presents obvious oscillation.With the enhancement of interaction,it is dissociated into polaron pairs,the spin-flip of which can be observed through modulating the interaction strength.For the triplet exciton,the strong electron-electron interaction restrains its normal polarization,but it is still stable.In the case of biexciton,the strong electron-electron interaction not only dissociate it,but also flip its charge distribution.The yield of the possible states formed after the dissociation of exciton and biexciton is also calculated.
基金Project supported by the Natural Science Basic Research Program of Shaanxi(Program Nos.2023KJXX-064 and 2021JQ-748)the National Natural Science Foundation of China(Grant Nos.11804213 and 12174238)Scientific Research Foundation of Shaanxi University of Technology(Grant No.SLGRCQD2006).
文摘We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-J model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response theory.An unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this state.The superconducting state with only spin-singlet pairs is dominant with paramagnetic phase.The A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a supercurrent.We also show the superfluid behavior of the unconventional superconducting state and its critical temperature.It is proven directly that the flat band can effectively raise the critical temperature of superconductivity.It is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial structures.Our results may help the understanding of the interplay between unconventional superconductivity and magnetism.
基金Supported by the National MCF Energy R&D Program under Grant No 2018YFE0311300the National Natural Science Foundation of China under Grant Nos 11875067,11835016,11705275,11675257 and 11675256+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDB16010300the Key Research Program of Frontier Science of Chinese Academy of Sciences under Grant No QYZDJ-SSW-SYS016the External Cooperation Program of Chinese Academy of Sciences under Grant No 112111KYSB20160039
文摘For an electron-electron collision with characteristic scale length larger than the relative gyro-radius of the two colliding electrons, when the initial relative parallel kinetic energy cannot surmount the Coulomb repulsive potential, reflection will occur with interchange of the parallel velocities of the two electrons after the collision. The Fokker–Planck approach is employed to derive the electron collision term C_R describing parallel velocity scattering due to the reflections for a magnetized plasma where the average electron gyro-radius is much smaller than the Debye length but much larger than the Landau length. The electron parallel velocity friction and diffusion coefficients due to the reflections are evaluated, which are found not to depend on the electron perpendicular velocity. By studying the temporal evolution of the H quantity due to CR, it is found that C_R eventually makes the system relax to a state in which the electron parallel velocity distribution is decoupled from the perpendicular velocity distribution.
基金Project supported by the National Natural Science Foundation of China (Grant No 10674084)
文摘We have studied the far-infrared spectra of two-electron vertically coupled quantum dots in an axial magnetic field by exact diagonalization. The calculated results show an obvious difference in role between the interactions for spin S = 1 and for spin S = O. The results support the possibility to evaluate the interactions by far-infrared spectroscopy in vertically coupled quantum dots.
基金Supported by the National Key Program for S&T Research and Development under Grant No 2016YFA0401100the National Basic Research Program of China under Grant No 2013CB922201the National Natural Science Foundation of China under Grant Nos 11504215,11374197,11334009 and 11425414
文摘The three-dimensional electron-electron correlation in an elliptically polarized laser field is investigated based on a semiclassical model. Asymmetry parameter α of the correlated electron momentum distribution is used to quantitatively describe the electron-electron correlation. The dependence of α on elliptieity e is totally different in three directions. For the z direction (maJor polarization direction), α first increases and reaches a maximum at ε = 0.275, then it decreases quickly. For the y direction in which the laser field is always absent, the ellipticity has a minor effect, and the asymmetry parameter fluctuates around α = -0.15. However, for the x direction (minor polarization direction), α increases monotonously with ellipticity though starts from the same value as in the y direction when ε = 0. The behavior of α in the x direction actually indicates a transformation from the Coulomb interaction dominated correlation to the laser field dominated correlation. Therefore, our work provides an efficient way to control the three-dimensional electron electron correlation via an elliptically polarized intense laser field.
文摘It is shown that the linear resistivity dependence on temperature for metals above the Debye’s temperature mainly is caused by electron-electron scattering of randomly moving electrons. The electron mean free path in metals at this temperature range is in inverse proportion to the effective density of randomly moving electrons, i.e. it is in inverse proportion both to the temperature, and to the density-of-states at the Fermi surface. The general relationships for estimation of the average diffusion coefficient, the average velocity, mean free length and average relaxation time of randomly moving electrons at the Fermi surface at temperatures above the Debye’s temperature are presented. The effective electron scattering cross-sections for different metals also are estimated. The calculation results of resistivity dependence on temperature in the range of temperature from 1 K to 900 K for Au, Cu, Mo, and Al also are presented and compared with the experimental data. Additionally in temperature range from 1 K to 900 K for copper, the temperature dependences of the mean free path, average diffusion coefficient, average drift mobility, average Hall mobility, average relaxation time of randomly moving electrons, and their resultant phonon mediated scattering cross-section are presented.
基金supported by the National Natural Science Foundation of China(Grant Nos.11474218 and 11575116)
文摘By using a multi-configurational time-dependent Hartree-Fock (MCTDHF) method for the time-dependent Schrrdinger equation and a Newtonian equation of motion for lattice, we investigate the disorder effects on the dissociation process of excitons in conjugated polymer chains. The simulations are performed within the framework of an extended version of the Su-Schrieffer-Heeger model modified to include on-site disorder, off-diagonal, electron-electron interaction, and an external electric field. Our results show that Coulomb correlation effects play an important role in determining the exciton dissociation process. The electric field required to dissociate an exciton can practically impossibly occur in a pure polymer chain, especially in the case of triplet exciton. However, when the on-site disorder effects are taken into account, this leads to a reduction in mean dissociation electric fields. As the disorder strength increases, the dissociation field decreases effectively. On the contrary, the effects of off-diagonal disorder are negative in most cases. Moreover, the dependence of exciton dissociation on the conjugated length is also discussed.
基金The project supported by National Natural Science Foundation of China under Grant No.10475021
文摘By using the exact diagonalization method,a system of three electrons confined in a parabolic quantumdot in zero magnetic field is studied.The ground-state electronic structures and orbital and spin angular momentatransitions as a function of the confined strength are investigated.We find that the confinement may cause accidentaldegeneracies between levels with different low-lying states and the inversion of the energy values.The present,resultsare useful to understanding the optical properties and internal electron-electron correlations of quantum dot materials.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774007 and U1832214)the National Key R&D Program of China(Grant No.2018YFA0305601)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB28000000).
文摘We grew single crystals of vanadium-substituted,ferromagnetic Weyl semimetal candidate Zr1-xVxCo1.6Sn from molten tin flux.These solid solutions all crystallize in a full Heusler structure(L21)while their Curie temperatures and magnetic moments are enhanced by V-substitution.Their resistivity gradually changes from bad-metal-like to semiconductor-like with increasing x while the anomalous Hall effect(AHE),which can be well fitted by Tian-Ye-Jin(TYJ)scaling,[1]is also enhanced.Moreover,we find an apparent electron-electron interaction(EEI)induced quantum correction in resistivity at low temperature.The anomalous Hall conductivity(AHC)dominated by the intrinsic term is not corrected.
基金Project supported by the National Natural Science Foundation of China (Grant No 10574162)partial supported from the Scientific Research Fund of GUCAS (Grant No 055101BM03)
文摘Based on relativistic multichannel theory, this paper calculates the energy levels of autoionization Rydberg series 4s^2nf(n=4- 23)J^π -(7/2)° of scandium at different levels of approximation within the framework of multichannel quantum defect theory. The present results show that the dipole polarizations play an important role. Considering the dynamical dipole polarization effects, this paper finds that the difference between calculated and experimental quantum defects for the 4s^2nf(n=4- 23)J^π -(7/2)° series is generally about 0.01- 0.03. Furthermore, the reason that 4s^216f is obscured in experimental spectra is suggested to be the interaction with the neighbouring resonance state converged to 3d^2(^1G4) of Sc^+.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10747002)Inner Mongolia Universities Science Research Project (Grant No. NJzc08158)
文摘This paper studies the two-electron total energy and the energy of the electron-electron interaction by using a variational method of Pekar type on the condition of electric-LO-phonon strong coupling in a parabolic quantum dot. It considers the following three cases: 1) two electrons are in the ground state; 2) one electron is in the ground state, the other is in the first-excited state; 3) two electrons are in the first-excited state. The relations of the two-electron total energy and the energy of the electron-electron interaction on the Coulomb binding parameter, the electron-LO-phonon coupling constant and the confinement length of the quantum dot are derived in the three cases.