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R K Janev - One of the best experts on this subject based on the ideXlab platform.
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resonances in nonrelativistic free free gaunt factors with screened Coulomb Interaction
Physical Review A, 2019Co-Authors: Jianguo Wang, R K Janev, Song Bin ZhangAbstract:The effect of Coulomb Interaction screening on non-relativistic free-free absorption is investigated by integrating the numerical continuum wave functions. The screened potential is taken to be in Debye-Hűckel (Yukawa) form with a screening length D. It is found that the values of the free-free Gaunt factors for different Debye screening lengths D for a given initial electron energy \eps_i and absorbing photon energy \omega, generally lie between those of the pure Coulomb field and field-free case. However, for initial electron energies below 0.1 Ry and fixed photon energy, the Gaunt factors show dramatic enhancements (broad and narrow resonances) in the vicinities of the critical screening lengths, Dnl, at which the energies of nl bound states in the potential merge into the continuum. These enhancements of the Gaunt factors can be significantly higher than their values in the unscreened (Coulomb) case over a broad range of \eps_i. The observed broad and narrow resonances in the Gaunt factors are related to the temporary formation of weakly bound (virtual) and resonant (quasi-bound) states of the low-energy initial electron on the Debye-Hűckel potential when the screening length is in the vicinity of Dnl.
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electron hydrogen atom elastic and inelastic scattering with screened Coulomb Interaction around the n 2 excitation threshold
Physical Review A, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron--hydrogen-atom elastic and excitation scattering around the $n=2$ threshold have been investigated by using the $R$-matrix method with pseudostates. The elastic and excitation collision strengths show dramatic changes when the Interaction screening length $D$ varies from $\ensuremath{\infty}$ to 3.8 a.u., as a result of the convergence of ${}^{1,3}S$ Feshbach resonances to the varying 2$s$ threshold and of the transformation of ${}^{1,3}P$ and ${}^{1}D$ Feshbach resonances into shape-type resonances when they pass across the 2$s$ and 2$p$ threshold at certain critical value of $D$, respectively [S. B. Zhang et al., Phys. Rev. Lett. 104, 023203 (2010)]. The resonance parameters for a large number of $D$ in the range $D=\ensuremath{\infty}$--3.8 a.u. are presented. It is observed that the ${}^{1,3}P$ and ${}^{1}D$ resonance contributions to the elastic and excitation collision strengths decrease rapidly with decreasing $D$ after the resonance passes the critical $D$ value. The contribution of a ${}^{1}{S}^{e}$ Feshbach resonance to the elastic or excitation collision strength changes into a cusp after the resonance merges into its parent 2$s$ state and immerses into the background with the further decrease of $D$.
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crossover of feshbach resonances to shape type resonances in electron hydrogen atom excitation with a screened Coulomb Interaction
Physical Review Letters, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron-hydrogen atom excitation in the n=2 threshold region are investigated by using the R-matrix method with pseudostates. The Interaction screening lifts the l degeneracy of n=2 Coulomb energy level, producing two distinct thresholds for 2s and 2p states. The phenomenon of transformation of {sup 1,3}P and {sup 1}D Feshbach resonances into shape-type resonances is observed when they pass across the 2s and 2p threshold, respectively, as the Interaction screening increases. It is shown that this resonance transformation leads to dramatic effects in the 1s->2s and 1s->2p excitation collision strengths in the n=2 threshold collision energy region.
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crossover of feshbach resonances to shape type resonances in electron hydrogen atom excitation with a screened Coulomb Interaction
Physical Review Letters, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron-hydrogen atom excitation in the $n=2$ threshold region are investigated by using the $R$-matrix method with pseudostates. The Interaction screening lifts the $l$ degeneracy of $n=2$ Coulomb energy level, producing two distinct thresholds for $2s$ and $2p$ states. The phenomenon of transformation of $^{1,3}P$ and $^{1}D$ Feshbach resonances into shape-type resonances is observed when they pass across the $2s$ and $2p$ threshold, respectively, as the Interaction screening increases. It is shown that this resonance transformation leads to dramatic effects in the $1s\ensuremath{\rightarrow}2s$ and $1s\ensuremath{\rightarrow}2p$ excitation collision strengths in the $n=2$ threshold collision energy region.
Song Bin Zhang - One of the best experts on this subject based on the ideXlab platform.
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resonances in nonrelativistic free free gaunt factors with screened Coulomb Interaction
Physical Review A, 2019Co-Authors: Jianguo Wang, R K Janev, Song Bin ZhangAbstract:The effect of Coulomb Interaction screening on non-relativistic free-free absorption is investigated by integrating the numerical continuum wave functions. The screened potential is taken to be in Debye-Hűckel (Yukawa) form with a screening length D. It is found that the values of the free-free Gaunt factors for different Debye screening lengths D for a given initial electron energy \eps_i and absorbing photon energy \omega, generally lie between those of the pure Coulomb field and field-free case. However, for initial electron energies below 0.1 Ry and fixed photon energy, the Gaunt factors show dramatic enhancements (broad and narrow resonances) in the vicinities of the critical screening lengths, Dnl, at which the energies of nl bound states in the potential merge into the continuum. These enhancements of the Gaunt factors can be significantly higher than their values in the unscreened (Coulomb) case over a broad range of \eps_i. The observed broad and narrow resonances in the Gaunt factors are related to the temporary formation of weakly bound (virtual) and resonant (quasi-bound) states of the low-energy initial electron on the Debye-Hűckel potential when the screening length is in the vicinity of Dnl.
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electron hydrogen atom elastic and inelastic scattering with screened Coulomb Interaction around the n 2 excitation threshold
Physical Review A, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron--hydrogen-atom elastic and excitation scattering around the $n=2$ threshold have been investigated by using the $R$-matrix method with pseudostates. The elastic and excitation collision strengths show dramatic changes when the Interaction screening length $D$ varies from $\ensuremath{\infty}$ to 3.8 a.u., as a result of the convergence of ${}^{1,3}S$ Feshbach resonances to the varying 2$s$ threshold and of the transformation of ${}^{1,3}P$ and ${}^{1}D$ Feshbach resonances into shape-type resonances when they pass across the 2$s$ and 2$p$ threshold at certain critical value of $D$, respectively [S. B. Zhang et al., Phys. Rev. Lett. 104, 023203 (2010)]. The resonance parameters for a large number of $D$ in the range $D=\ensuremath{\infty}$--3.8 a.u. are presented. It is observed that the ${}^{1,3}P$ and ${}^{1}D$ resonance contributions to the elastic and excitation collision strengths decrease rapidly with decreasing $D$ after the resonance passes the critical $D$ value. The contribution of a ${}^{1}{S}^{e}$ Feshbach resonance to the elastic or excitation collision strength changes into a cusp after the resonance merges into its parent 2$s$ state and immerses into the background with the further decrease of $D$.
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crossover of feshbach resonances to shape type resonances in electron hydrogen atom excitation with a screened Coulomb Interaction
Physical Review Letters, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron-hydrogen atom excitation in the n=2 threshold region are investigated by using the R-matrix method with pseudostates. The Interaction screening lifts the l degeneracy of n=2 Coulomb energy level, producing two distinct thresholds for 2s and 2p states. The phenomenon of transformation of {sup 1,3}P and {sup 1}D Feshbach resonances into shape-type resonances is observed when they pass across the 2s and 2p threshold, respectively, as the Interaction screening increases. It is shown that this resonance transformation leads to dramatic effects in the 1s->2s and 1s->2p excitation collision strengths in the n=2 threshold collision energy region.
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crossover of feshbach resonances to shape type resonances in electron hydrogen atom excitation with a screened Coulomb Interaction
Physical Review Letters, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron-hydrogen atom excitation in the $n=2$ threshold region are investigated by using the $R$-matrix method with pseudostates. The Interaction screening lifts the $l$ degeneracy of $n=2$ Coulomb energy level, producing two distinct thresholds for $2s$ and $2p$ states. The phenomenon of transformation of $^{1,3}P$ and $^{1}D$ Feshbach resonances into shape-type resonances is observed when they pass across the $2s$ and $2p$ threshold, respectively, as the Interaction screening increases. It is shown that this resonance transformation leads to dramatic effects in the $1s\ensuremath{\rightarrow}2s$ and $1s\ensuremath{\rightarrow}2p$ excitation collision strengths in the $n=2$ threshold collision energy region.
M S Bahramy - One of the best experts on this subject based on the ideXlab platform.
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interplay of spin orbit coupling and Coulomb Interaction in zno based electron system
Nature Communications, 2021Co-Authors: D Maryenko, Minoru Kawamura, A Ernst, V K Dugaev, Ya E Sherman, M Kriener, M S BahramyAbstract:Spin–orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these phenomena have been so far studied in relatively weak electron–electron Interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb Interaction, which could lead to the emergence of unconventional electronic phases. Since SOC depends on the electric field in the crystal including contributions of itinerant electrons, electron–electron Interactions can modify this coupling. Here we demonstrate the emergence of the SOC effect in a high-mobility two-dimensional electron system in a simple band structure MgZnO/ZnO semiconductor. This electron system also features strong electron–electron Interaction effects. By changing the carrier density with Mg-content, we tune the SOC strength and achieve its interplay with electron–electron Interaction. These systems pave a way to emergent spintronic phenomena in strong electron correlation regimes and to the formation of quasiparticles with the electron spin strongly coupled to the density. The coexistence of spin–orbit and electron–electron Interactions is expected to give rise to novel electronic phases and spin textures, but it is challenging to achieve in experiments. Here the authors realize such a regime in a two-dimensional electron system at a MgZnO/ZnO interface, by tuning the carrier density.
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interplay of spin orbit coupling and Coulomb Interaction in zno based electron system
arXiv: Mesoscale and Nanoscale Physics, 2020Co-Authors: D Maryenko, Minoru Kawamura, A Ernst, V K Dugaev, Ya E Sherman, M Kriener, M S BahramyAbstract:Spin-orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these phenomena have been so far studied in relatively weak electron-electron Interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb Interaction, which could lead to the emergence of unconventional electronic phases. Since SOC depends on the electric field in the crystal including contributions of itinerant electrons, electron-electron Interactions can modify this coupling. Here we demonstrate the emergence of SOC effect in a high-mobility two-dimensional electron system in a simple band structure MgZnO/ZnO semiconductor. This electron system features also strong electron-electron Interaction effects. By changing the carrier density with Mg-content, we tune the SOC strength and achieve its interplay with electron-electron Interaction. These systems pave a way to emergent spintronic phenomena in strong electron correlation regime and to the formation of novel quasiparticles with the electron spin strongly coupled to the density.
Jianguo Wang - One of the best experts on this subject based on the ideXlab platform.
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resonances in nonrelativistic free free gaunt factors with screened Coulomb Interaction
Physical Review A, 2019Co-Authors: Jianguo Wang, R K Janev, Song Bin ZhangAbstract:The effect of Coulomb Interaction screening on non-relativistic free-free absorption is investigated by integrating the numerical continuum wave functions. The screened potential is taken to be in Debye-Hűckel (Yukawa) form with a screening length D. It is found that the values of the free-free Gaunt factors for different Debye screening lengths D for a given initial electron energy \eps_i and absorbing photon energy \omega, generally lie between those of the pure Coulomb field and field-free case. However, for initial electron energies below 0.1 Ry and fixed photon energy, the Gaunt factors show dramatic enhancements (broad and narrow resonances) in the vicinities of the critical screening lengths, Dnl, at which the energies of nl bound states in the potential merge into the continuum. These enhancements of the Gaunt factors can be significantly higher than their values in the unscreened (Coulomb) case over a broad range of \eps_i. The observed broad and narrow resonances in the Gaunt factors are related to the temporary formation of weakly bound (virtual) and resonant (quasi-bound) states of the low-energy initial electron on the Debye-Hűckel potential when the screening length is in the vicinity of Dnl.
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electron hydrogen atom elastic and inelastic scattering with screened Coulomb Interaction around the n 2 excitation threshold
Physical Review A, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron--hydrogen-atom elastic and excitation scattering around the $n=2$ threshold have been investigated by using the $R$-matrix method with pseudostates. The elastic and excitation collision strengths show dramatic changes when the Interaction screening length $D$ varies from $\ensuremath{\infty}$ to 3.8 a.u., as a result of the convergence of ${}^{1,3}S$ Feshbach resonances to the varying 2$s$ threshold and of the transformation of ${}^{1,3}P$ and ${}^{1}D$ Feshbach resonances into shape-type resonances when they pass across the 2$s$ and 2$p$ threshold at certain critical value of $D$, respectively [S. B. Zhang et al., Phys. Rev. Lett. 104, 023203 (2010)]. The resonance parameters for a large number of $D$ in the range $D=\ensuremath{\infty}$--3.8 a.u. are presented. It is observed that the ${}^{1,3}P$ and ${}^{1}D$ resonance contributions to the elastic and excitation collision strengths decrease rapidly with decreasing $D$ after the resonance passes the critical $D$ value. The contribution of a ${}^{1}{S}^{e}$ Feshbach resonance to the elastic or excitation collision strength changes into a cusp after the resonance merges into its parent 2$s$ state and immerses into the background with the further decrease of $D$.
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crossover of feshbach resonances to shape type resonances in electron hydrogen atom excitation with a screened Coulomb Interaction
Physical Review Letters, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron-hydrogen atom excitation in the n=2 threshold region are investigated by using the R-matrix method with pseudostates. The Interaction screening lifts the l degeneracy of n=2 Coulomb energy level, producing two distinct thresholds for 2s and 2p states. The phenomenon of transformation of {sup 1,3}P and {sup 1}D Feshbach resonances into shape-type resonances is observed when they pass across the 2s and 2p threshold, respectively, as the Interaction screening increases. It is shown that this resonance transformation leads to dramatic effects in the 1s->2s and 1s->2p excitation collision strengths in the n=2 threshold collision energy region.
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crossover of feshbach resonances to shape type resonances in electron hydrogen atom excitation with a screened Coulomb Interaction
Physical Review Letters, 2010Co-Authors: Song Bin Zhang, Jianguo Wang, R K JanevAbstract:The effects of Coulomb Interaction screening on electron-hydrogen atom excitation in the $n=2$ threshold region are investigated by using the $R$-matrix method with pseudostates. The Interaction screening lifts the $l$ degeneracy of $n=2$ Coulomb energy level, producing two distinct thresholds for $2s$ and $2p$ states. The phenomenon of transformation of $^{1,3}P$ and $^{1}D$ Feshbach resonances into shape-type resonances is observed when they pass across the $2s$ and $2p$ threshold, respectively, as the Interaction screening increases. It is shown that this resonance transformation leads to dramatic effects in the $1s\ensuremath{\rightarrow}2s$ and $1s\ensuremath{\rightarrow}2p$ excitation collision strengths in the $n=2$ threshold collision energy region.
Jozef Spalek - One of the best experts on this subject based on the ideXlab platform.
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universal properties of high temperature superconductors from real space pairing role of correlated hopping and intersite Coulomb Interaction within the t j u model
Physical Review B, 2017Co-Authors: M Zegrodnik, Jozef SpalekAbstract:We study the effect of the correlated hopping term and the intersite Coulomb Interaction term on principal features of the $d$-$wave$ superconducting (SC) state, in both the electron and hole doped regimes within the t-J-U model. In our analysis we use the approach based on the diagrammatic expansion of the Gutzwiller wave function (DE-GWF) which allows us to go beyond the renormalized mean field theory (RMFT). We show that the correlated hopping term enhances the pairing at the electron-doped side of the phase diagram. Moreover, the so-called non-BCS regime (which manifests itself by the negative kinetic energy gain at the transition to the SC phase) is narrowed down with the increasing magnitude of the correlated hopping $\sim K$. Also, the doping dependences of the nodal Fermi velocity and Fermi momentum, as well as the average number of double occupancies, are analyzed with reference to the experimental data for selected values of the parameter $K$. For the sake of completeness, the influence of the intersite Coulomb repulsion on the obtained results is provided. Additionally, selected results concerning the Hubbard-model case are also presented. A complete model with all two-site Interactions is briefly discussed in the Appendix for reference.
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universal properties of high temperature superconductors from real space pairing role of correlated hopping and intersite Coulomb Interaction within the t j u model
Physical Review B, 2017Co-Authors: M Zegrodnik, Jozef SpalekAbstract:We study the effect of the correlated hopping term and the intersite Coulomb Interaction term on principal features of the $d$-wave superconducting (SC) state, in both the electron- and hole-doped regimes within the $t\text{\ensuremath{-}}J\text{\ensuremath{-}}U$ model. In our analysis, we use the approach based on the diagrammatic expansion of the Gutzwiller wave function (DE-GWF), which allows us to go beyond the renormalized mean-field theory (RMFT). We show that the correlated hopping term enhances the pairing at the electron-doped side of the phase diagram. Moreover, the so-called non-BCS regime (which manifests itself by the negative kinetic energy gain at the transition to the SC phase) is narrowed down with the increasing magnitude of the correlated hopping $\ensuremath{\sim}K$. Also, the doping dependencies of the nodal Fermi velocity and Fermi momentum, as well as the average number of double occupancies, are analyzed with reference to the experimental data for selected values of the parameter $K$. For the sake of completeness, the influence of the intersite Coulomb repulsion on the obtained results is provided. Additionally, selected results concerning the Hubbard-model case are also presented. A complete model with all two-site Interactions is briefly discussed in Appendix for reference.
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antiferromagnetism charge density wave and d wave superconductivity in the extended t j u model role of intersite Coulomb Interaction and a critical overview of renormalized mean field theory
arXiv: Strongly Correlated Electrons, 2016Co-Authors: Marcin Abram, M Zegrodnik, Jozef SpalekAbstract:In the first part of the paper, we study the stability of antiferromagnetic (AF), charge density wave (CDW), and superconducting (SC) states within the $t$-$J$-$U$-$V$ model of strongly correlated electrons by using the statistically consistent Gutzwiller approximation (SGA). We concentrate on the role of the intersite Coulomb Interaction term $V$ in stabilizing the CDW phase. In particular, we show that the charge ordering appears only above a critical value of $V$ in a limited hole-doping range $\delta$. The effect of the $V$ term on SC and AF phases is that a strong Interaction suppresses SC, whereas the AF order is not significantly influenced by its presence. In the second part, separate calculations for the case of pure SC phase have been carried out within an extended approach (the diagrammatic expansion for the Gutzwiller wave function, DE-GWF) in order to analyze the influence of the intersite Coulomb repulsion on the SC phase with the higher-order corrections included beyond the SGA method. In the Appendices we discuss the ambiguity connected with the choice of the Gutzwiller renormalization factors within the renormalized mean filed theory when either AF or CDW orders are considered. At the end we overview briefly the possible extensions of the current models to make description of the SC, AF, and CDW states on equal footing.
