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Chi Ho Cheng - One of the best experts on this subject based on the ideXlab platform.
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supersymmetry in models with strong on site Coulomb Repulsion application to the heisenberg model
Physical Review B, 1999Co-Authors: Chi Ho ChengAbstract:A supersymmetric way of imposing the constraint of no double occupancy in models with strong on-site Coulomb Repulsion is presented in this paper. In this formulation the physical operators in the constrainted Hilbert space are invariant under local unitary transformations mixing boson and fermion representations. As an illustration the formulation is applied to the $t-J$ model. The model is studied in the mean-field level in the J=0 limit where we show how both the slave-boson and slave-fermion formulations are included naturally in the present approach and how further results beyond both approaches are obtained.
A. F. Barabanov - One of the best experts on this subject based on the ideXlab platform.
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Influence of the Coulomb Repulsions on the Formation of the Superconducting Gap of the Spin-Polaron Quasiparticles in Cuprates
Journal of Low Temperature Physics, 2018Co-Authors: V. V. Val’kov, M. M. Korovushkin, A. F. BarabanovAbstract:Taking into account the real crystalline structure of the $$\hbox {CuO}_2$$ plane and the strong spin-fermion coupling, the influence of the on-site Coulomb Repulsion of holes $$U_p$$ and the intersite Coulomb Repulsion $$V_2$$ between holes located at the next-nearest-neighbor oxygen ions on the formation of the superconducting gap with the d-wave symmetry of the order parameter of the spin-polaron quasiparticles is studied. It is shown that the formation of the resulting superconducting gap within the spin-fermion model is caused by three components. The dependence of the narrowing of the superconducting gap on the values $$U_p$$ and $$V_2$$ is analyzed.
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stability of the superconducting d wave pairing toward the intersite Coulomb Repulsion in hbox cuo _2 plane
Journal of Low Temperature Physics, 2018Co-Authors: V V Valkov, M. M. Korovushkin, D M Dzebisashvili, A. F. BarabanovAbstract:Taking into account the real crystalline structure of the \(\hbox {CuO}_2\) plane and the strong spin-fermion coupling, we study the influence of the intersite Coulomb Repulsion between holes on the Cooper instability of the spin-polaron quasiparticles in cuprate superconductors. The analysis shows that only the superconducting d-wave pairing is implemented in the whole region of doping, whereas the solutions of the self-consistent equations for the s-wave pairing are absent. It is shown that intersite Coulomb interaction \(V_1\) between the holes located at the nearest oxygen ions does not affect the d-wave pairing, because its Fourier transform \(V_q\) vanishes in the kernel of the corresponding integral equation. The intersite Coulomb interaction \(V_2\) of quasiparticles located at the next-nearest oxygen ions does not vanish in the integral equations, however, but it is also shown that the d-wave pairing is robust toward this interaction for physically reasonable values of \(V_2\).
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Coulomb Repulsion of holes and competition between d_ x 2 y 2 wave and s wave parings in cuprate superconductors
Journal of Experimental and Theoretical Physics, 2017Co-Authors: V V Valkov, M. M. Korovushkin, D M Dzebisashvili, A. F. BarabanovAbstract:The effect of the Coulomb Repulsion of holes on the Cooper instability in an ensemble of spin–polaron quasiparticles has been analyzed, taking into account the peculiarities of the crystallographic structure of the CuO2 plane, which are associated with the presence of two oxygen ions and one copper ion in the unit cell, as well as the strong spin–fermion coupling. The investigation of the possibility of implementation of superconducting phases with d-wave and s-wave of the order parameter symmetry has shown that in the entire doping region only the d-wave pairing satisfies the self-consistency equations, while there is no solution for the s-wave pairing. This result completely corresponds to the experimental data on cuprate HTSC. It has been demonstrated analytically that the intersite Coulomb interaction does not affect the superconducting d-wave pairing, because its Fourier transform V q does not appear in the kernel of the corresponding integral equation.
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stability of the superconducting d_ x 2 y 2 phase in high t c superconductors with respect to the intersite Coulomb Repulsion of holes at oxygen
Jetp Letters, 2016Co-Authors: V V Valkov, M. M. Korovushkin, D M Dzebisashvili, A. F. BarabanovAbstract:It has been shown that, because of the two-orbital character of the subsystem of holes located at oxygen sites and the spatial separation of this subsystem from that of spins at copper ions, the superconducting phase in high-T c superconductors is stable with respect to the strong Coulomb Repulsion of holes located at nearestneighbor oxygen sites if the order parameter has the \({d_{{x^2} - {y^2}}}\) symmetry. This effect is due to the symmetry characteristics of the Coulomb potential, owing to which the equation determining the Cooper pairing in the \({d_{{x^2} - {y^2}}}\) channel does not include this potential.
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stability of the superconducting d_ x 2 y 2 wave pairing towards the intersite Coulomb Repulsion between oxygen holes in high t _c superconductors
arXiv: Superconductivity, 2016Co-Authors: V V Valkov, M. M. Korovushkin, D M Dzebisashvili, A. F. BarabanovAbstract:It is shown that an account for the space separatedness of the two-orbital subsystem of the oxygen holes and the subsystem of the localized spins of copper ions in high-T$_c$ cuprate superconductors leads to the stability of the superconducting $d_{x^2-y^2}$-wave pairing towards the strong Coulomb Repulsion between holes located at the nearest oxygen ions. This effect is due to the fact that the Coulomb potential slips out of the equation for the Cooper pairing in the $d_{x^2-y^2}$-wave channel owing to the properties of symmetry.
V V Valkov - One of the best experts on this subject based on the ideXlab platform.
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stability of the superconducting d wave pairing toward the intersite Coulomb Repulsion in hbox cuo _2 plane
Journal of Low Temperature Physics, 2018Co-Authors: V V Valkov, M. M. Korovushkin, D M Dzebisashvili, A. F. BarabanovAbstract:Taking into account the real crystalline structure of the \(\hbox {CuO}_2\) plane and the strong spin-fermion coupling, we study the influence of the intersite Coulomb Repulsion between holes on the Cooper instability of the spin-polaron quasiparticles in cuprate superconductors. The analysis shows that only the superconducting d-wave pairing is implemented in the whole region of doping, whereas the solutions of the self-consistent equations for the s-wave pairing are absent. It is shown that intersite Coulomb interaction \(V_1\) between the holes located at the nearest oxygen ions does not affect the d-wave pairing, because its Fourier transform \(V_q\) vanishes in the kernel of the corresponding integral equation. The intersite Coulomb interaction \(V_2\) of quasiparticles located at the next-nearest oxygen ions does not vanish in the integral equations, however, but it is also shown that the d-wave pairing is robust toward this interaction for physically reasonable values of \(V_2\).
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Coulomb Repulsion of holes and competition between d_ x 2 y 2 wave and s wave parings in cuprate superconductors
Journal of Experimental and Theoretical Physics, 2017Co-Authors: V V Valkov, M. M. Korovushkin, D M Dzebisashvili, A. F. BarabanovAbstract:The effect of the Coulomb Repulsion of holes on the Cooper instability in an ensemble of spin–polaron quasiparticles has been analyzed, taking into account the peculiarities of the crystallographic structure of the CuO2 plane, which are associated with the presence of two oxygen ions and one copper ion in the unit cell, as well as the strong spin–fermion coupling. The investigation of the possibility of implementation of superconducting phases with d-wave and s-wave of the order parameter symmetry has shown that in the entire doping region only the d-wave pairing satisfies the self-consistency equations, while there is no solution for the s-wave pairing. This result completely corresponds to the experimental data on cuprate HTSC. It has been demonstrated analytically that the intersite Coulomb interaction does not affect the superconducting d-wave pairing, because its Fourier transform V q does not appear in the kernel of the corresponding integral equation.
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stability of the superconducting d_ x 2 y 2 phase in high t c superconductors with respect to the intersite Coulomb Repulsion of holes at oxygen
Jetp Letters, 2016Co-Authors: V V Valkov, M. M. Korovushkin, D M Dzebisashvili, A. F. BarabanovAbstract:It has been shown that, because of the two-orbital character of the subsystem of holes located at oxygen sites and the spatial separation of this subsystem from that of spins at copper ions, the superconducting phase in high-T c superconductors is stable with respect to the strong Coulomb Repulsion of holes located at nearestneighbor oxygen sites if the order parameter has the \({d_{{x^2} - {y^2}}}\) symmetry. This effect is due to the symmetry characteristics of the Coulomb potential, owing to which the equation determining the Cooper pairing in the \({d_{{x^2} - {y^2}}}\) channel does not include this potential.
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stability of the superconducting d_ x 2 y 2 wave pairing towards the intersite Coulomb Repulsion between oxygen holes in high t _c superconductors
arXiv: Superconductivity, 2016Co-Authors: V V Valkov, M. M. Korovushkin, D M Dzebisashvili, A. F. BarabanovAbstract:It is shown that an account for the space separatedness of the two-orbital subsystem of the oxygen holes and the subsystem of the localized spins of copper ions in high-T$_c$ cuprate superconductors leads to the stability of the superconducting $d_{x^2-y^2}$-wave pairing towards the strong Coulomb Repulsion between holes located at the nearest oxygen ions. This effect is due to the fact that the Coulomb potential slips out of the equation for the Cooper pairing in the $d_{x^2-y^2}$-wave channel owing to the properties of symmetry.
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triplet p wave superconductivity in the low density extended hubbard model with Coulomb Repulsion
Jetp Letters, 2011Co-Authors: Yu M Kagan, D V Efremov, M S Marienko, V V ValkovAbstract:We analyze superconducting instabilities in 3D and 2D extended Hubbard model with Coulomb Repulsion between electrons on neighboring sites in the limit of low electron density (n el → 0) on simple cubic (square) lattice. We show that in a realistic strong-coupling case U ≫ V ≫ W (U and V are the onsite and the intersite Coulomb Repulsions, respectively, and W the bandwidth) the main SC instability corresponds to the p-wave pairing and in the leading order is correctly described by the equations obtained earlier in the absence of the intersite Coulomb interaction V = 0.
Peter Hanggi - One of the best experts on this subject based on the ideXlab platform.
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coherent charge transport through molecular wires exciton blocking and current from electronic excitations in the wire
Physical Review B, 2010Co-Authors: Peter Hanggi, Sigmund Kohler, B D Fainberg, Abraham Nitzan, Beverly SacklerAbstract:We consider exciton effects on current in molecular nanojunctions, using a model comprising a two twolevel sites bridge connecting free-electron reservoirs. Expanding the density operator in the many-electron eigenstates of the uncoupled sites, we obtain a 16 16 density matrix in the bridge subspace whose dynamics is governed by Liouville equation that takes into account interactions on the bridge as well as electron injection and damping to and from the leads. Our consideration can be considerably simplified by using the pseudospin description based on the symmetry properties of Lie group SU2. We study the influence of the bias voltage, the Coulomb Repulsion, and the energy-transfer interactions on the steady-state current and, in particular, focus on the effect of the excitonic interaction between bridge sites. Our calculations show that in case of noninteracting electrons this interaction leads to reduction in the current at high voltage for a homodimer bridge. In other words, we predict the effect of “exciton” blocking. The effect of exciton blocking is modified for a heterodimer bridge and disappears for strong Coulomb Repulsion at sites. In the latter case the exciton type interactions can open new channels for electronic conduction. In particular, in the case of strong Coulomb Repulsion, conduction exists even when the electronic connectivity does not exist.
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Coulomb Repulsion effects in driven electron transport
European Physical Journal B, 2006Co-Authors: Franz J Kaiser, Peter Hanggi, Sigmund KohlerAbstract:We study numerically the influence of strong Coulomb Repulsion on the current through molecular wires that are driven by external electromagnetic fields. The molecule is described by a tight-binding model whose first and last site is coupled to a respective lead. The leads are eliminated within a perturbation theory yielding a master equation for the wire. The decomposition into a Floquet basis enables an efficient treatment of the driving field. For the electronic excitations in bridged molecular wires, we find that strong Coulomb Repulsion significantly sharpens resonance peaks which broaden again with increasing temperature. By contrast, it has only a small influence on effects like non-adiabatic electron pumping and coherent current suppression.
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coherent charge transport through molecular wires influence of strong Coulomb Repulsion
Chemical Physics, 2006Co-Authors: Franz J Kaiser, Sigmund Kohler, Michael Strass, Peter HanggiAbstract:We derive a master equation for the electron transport through molecular wires in the limit of strong Coulomb Repulsion. This approach is applied to two typical situations: First, we study transport through an open conduction channel for which we find that the current exhibits an ohmic-like behaviour. Second, we explore the transport properties of a bridged molecular wire, where the current decays exponentially as a function of the wire length. For both situations, we discuss the differences to the case of non-interacting electrons.
Patrick Rousseau - One of the best experts on this subject based on the ideXlab platform.
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dynamics of glycine dications in the gas phase ultrafast intramolecular hydrogen migration versus Coulomb Repulsion
Journal of Physical Chemistry Letters, 2013Co-Authors: S Maclot, Dariusz Grzegorz Piekarski, A Domaracka, A Mery, V Vizcaino, L Adoui, F Martin, Manuel Alcami, B A Huber, Patrick RousseauAbstract:We present a combined experimental and theoretical study of the complex dynamics of excited doubly ionized glycine molecules in the gas phase. Multicoincidence mass spectroscopic techniques together with ab initio molecular dynamics simulations and density functional theory calculations allow us to show that an ultrafast intramolecular hydrogen migration (∼30 fs) appears in competiton with the expected Coulomb Repulsion.
