Doping dependence of bose condensation energy and correlations with spectral peak intensity and superfluid weight in high Tc cuprates

Based on our recent holon-pair boson theory of the t-J Hamiltonian (Phys. Rev. B 64, 052501 (2001)) we report the doping dependence of the bose condensation energy, superfluid weight and spectral peak intensity. We find a universality of doping dependence in these physical quantities, by equally showing an arch shape in the variations of their magnitudes with the hole doping concentration. We find that all of these physical quantities scale well with the positive charge carrier (hole) density x, but not with the electron density 1-x for the entire range of hole doping. It is shown that the doping dependence of the condensation energy U at T = 0 K is given by the relation, $U(0) \approx \alpha x^2 |\Delta_0|^2$ with $\Delta_0$, the pairing gap at 0 K and $\alpha$, a constant.Comment: 5 pages, 2 figure

Holon-pair boson theory based on the U(1) and SU(2) slave-boson approaches to the t-J Hamiltonian

To supplement our recent brief report on the theory of holon-pair boson approach to the t-J Hamiltonian [S.-S. Lee and Sung-Ho Suck Salk, Phys. Rev. B {\bf 64}, 052501(2001)], in this paper we present a full exposure to the theory, detailed physical implications and predicted various physical properties of high $T_c$ cuprates. We discuss the significance of coupling (interplay) between the spin and charge degrees of freedom in the Heisenberg interaction term of the t-J Hamiltonian. We discuss its importance in causing the arch-shaped superconducting transition temperature $T_c$ and the pseudogap (spin gap) temperature $T^*$ tangential to $T_c$ in the overdoped region in the observed phase diagram of high $T_c$ cuprates. A universal parabolic scaling behavior of $T^*/T_c$ (or $T_c/T^*$) with hole doping concentration is predicted in agreement with observations, indicating that there exists correlation between the pseudogap (spin gap) phase and the superconducting phase through antiferromagnetic fluctuations. Our proposed holon-pair boson theory is shown to be self-consistent in that it not only yields the arch (dome) shape structure of $T_c$ but also reproduces various other physical properties such as superfluid weight, bose condensation energy, spectral function, optical conductivity and spin susceptibility, including their temperature and doping dependence

Origin of the Quasiparticle Peaks of Spectral Functions in High TcT_c Cuprates

Based on the SU(2) slave-boson approach to the t-J Hamiltonian, we examine the cause of the sharp peaks('quasiparticle' peaks) in the observed spectral functions in high $T_c$ cuprates. The computed results reveal that the spectral weight of the sharp peaks increases with hole doping rate in agreement with observation. It is shown that the observed sharp peaks are attributed to the enhancement of spinon pairing(spin singlet pair formation) by the presence of holon pair bosons in the superconducting state.Comment: 4 pages, 6 figure

Holon Pair Bose Condensation in High TcT_c Cuprates; Symmetry Breaking and Supersymmetry Conditions

Using the t-J Hamiltonian of U(1) slave-boson symmetry, bose condensation is discussed by showing the occurrence of symmetry breaking in the hole doped high $T_c$ cuprates. The symmetry breaking is shown to take place with the d-wave hole pairing, but not with the s-wave hole pairing. Based on a derived supersymmetry Hamiltonian we find that there exists a possibility of supersymmetry conditions in association with the pairing order parameters of both spinon and holon.Comment: 4 pages, 2 figure

Doping and temperature dependence of superfluid weights for high Tc cuprates

Using the improved slave-boson approach of the t-J Hamiltonian [Phys. Rev. B 64, 052501 (2001)] that we developed recently, we report the hole doping and temperature dependence of the superfluid weight. It is shown that at low hole doping concentration x and at low temperatures T there exists a propensity of a linear decrease of the superfluid weight $n_s/m^*$ with temperature, and a tendency of doping independence in the slope of $\frac{n_s}{m^*}(x,T)$ vs. T in accordance of the relation $\frac{n_s}{m^*}(x,T) = \frac{n_s}{m^*}(x,0) - \alpha T$ with $\alpha$, a constant. It is also demonstrated that Tc increases with hole doping concentration x, reaches a saturation(maximum) at optimal doping and decreases with increasing $x$ and $n_s/m^*$ in the overdoped region. Such a reflex (decreasing) behavior of Tc is attributed to the weakening of coupling between the spin(spinon pair order) and charge(holon pair order) degrees of freedom in the overdoped region. All of these findings are in agreement with $\mu$SR measurements.Comment: 6 pages, 5 figure

Undulatory Variation of Antiferromagnetic Strength with Magnetic Field Based on Hubbard Model Hamiltonian

Using the Hubbard model Hamiltonian in a mean field level, we examine the variation of antiferromagnetic strength with applied magnetic field. It is demonstrated that minima in the antiferromagnetic strength exist at the the even integer denominator values of rational number for magnetic flux per plaquette. The undulatory behavior of antiferromagnetic strength with the external magnetic field is found. It is seen to be related to the undulatory net statistical phase owing to the influence of the applied magnetic field.Comment: 11 pages, 3 Postscript figure

Holon Pairing Instability based on the Bethe-Salpeter Equation obtained from the t-J Hamiltonians of both U(1) and SU(2) Slave-boson Symmetries

We investigate a possibility of holon pairing for bose condensation based on the Bethe-Salpeter equation obtained from the use of the t-J Hamiltonians of both t he U(1) and SU(2) slave-boson symmetries. It is shown that the vertex function contributed from ladder diagram series involving holon-holon scattering channel in the Bethe-Salpeter equation leads to a singular behavior at a critical temperature at each hole doping concentration, showing the instability of the normal state against holon pairing. We find that the holon pairing instability occurs only in a limited range of hole doping, by showing an "arch" shaped bose condensation line in agreement with observation for high $T_c$ cuprates. It is revealed that this is in agreement with a functional integral approach of the slave-boson theories.Comment: 4 pages, 5 figure

Universal scaling behavior of pseudogap with doping in high Tc cuprates; temperature and doping dependence of spectral intensity

Based on our improved SU(2) slave-boson approach (Phys. Rev. B 64, 052501(2001)) to the t-J Hamiltonian, we report a scaling behavior of pseudogap with doping and the temperature and doping dependence of spectral functions. In addition we discuss the cause of hump and quasi-particle peak in the observed spectral functions of high Tc cuprates. It is demonstrated that the sharpening of the observed quasi-particle peak below Tc is attributed to the bose condensation of holon pair. From the computed ratios of pseudogap $\Delta_0$ to both the superconducting temperature Tc and the pseudogap temperature $T^*$ as a function of hole doping concentration x, we find that there exists a universal scaling of these ratios with doping, that is, the hyperbolic scaling behavior of the former, $\frac{2 \Delta_0}{k_B T_c} \sim x^{-\alpha}$ with $\alpha \sim 2$ and near doping independence of the latter, $\frac{2 \Delta_0}{k_B T^*} \approx 4 \sim 6$ are found.Comment: 5 pages, 5 figure

The Fermion Chern-Simons Gauge Theory of Fractional Quantum Hall Effect for Electromagnetic Polarization Tensor

Unlike an earlier theory, by avoiding both the electromagnetic gauge field shift and the assumption of the zero average of electromagnetic field fluctuation the fermion Chern-Simons gauge theory is reformulated to obtain mean field solutions and a self-consistent expression of the electromagnetic polarization tensor in terms of the composite fermion picture for the systems of fractional quantum Hall effect. Thus the newly derived electromagnetic polarization tensor is shown to depend on the residual (effective) magnetic field `seen' by composite fermions rather than the statistical field, which differs from the earlier theory. The present theory reproduces the Hall conductance of fractional quantum Hall effect. The self-consistent picture of the composite fermion is maintained in all of our derivations: both the mean field solutions and the electromagnetic polarization tensor are described by the residual magnetic field seen by the composite fermions.Comment: 10 pages, Phys. Rev. B in pres

Quasiparticle Energy Dispersion and Shadow Peaks in a Doped SO(5) Symmetric Ladder

Mean field and exact diagonalization studies on the quasiparticle excitation of an SO(5) symmetric two-leg ladder system are reported. It is shown that the energy gap in the quasiparticle excitation is caused by the formation of rung singlet states. We find that shadow peaks can occur above the Fermi surface with antiferromagnetic electron correlations involving only rungs in the spin ladder.Comment: 13 pages, 4 figure