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Within the t-t'-J model, the doping dependence of the Meissner effect in cuprate superconductors is studied based on the kinetic energy driven superconducting mechanism. Following the linear response theory, it is shown that the electromagnetic response consists of two parts, the diamagnetic current and the paramagnetic current, which exactly cancels the diamagnetic term in the normal state, and then the Meissner effect is obtained for all the temperature $T\leq T_{c}$ throughout the superconducting dome. By considering the two-dimensional geometry of cuprate superconductors within the specular reflection model, the main features of the doping and temperature dependence of the local magnetic field profile, the magnetic field penetration depth, and the superfluid density observed on cuprate superconductors are well reproduced. In particular, it is shown that in analogy to the domelike shape of the doping dependent superconducting transition temperature, the maximal superfluid density occurs around the critical doping $\delta\approx 0.195$, and then decreases in both lower doped and higher doped regimes.Comment: 13 pages, 5 figure

Within the framework of the kinetic energy driven superconductivity, the electromagnetic response in cuprate superconductors is studied in the linear response approach. The kernel of the response function is evaluated and employed to calculate the local magnetic field profile, the magnetic field penetration depth, and the superfluid density, based on the specular reflection model for a purely transverse vector potential. It is shown that the low temperature magnetic field profile follows an exponential decay at the surface, while the magnetic field penetration depth depends linearly on temperature, except for the strong deviation from the linear characteristics at extremely low temperatures. The superfluid density is found to decrease linearly with decreasing doping concentration in the underdoped regime. The problem of gauge invariance is addressed and an approximation for the dressed current vertex, which does not violate local charge conservation is proposed and discussed.

A long-standing puzzle is why there is a difference between the optimal doping δ optimal ≈ 0.15 for the maximal superconducting (SC) transition temperature Tc and the critical doping δ critical ≈ 0.19 for the highest superfluid density ρs in cuprate superconductors? This puzzle is calling for an explanation. Within the kinetic energy driven SC mechanism, it is shown that except the quasiparticle coherence, ρs is dominated by the bare pair gap, while Tc is set by the effective pair gap. By calculation of the ratio of the effective and the bare pair gaps, it is shown that the coupling strength decreases with increasing doping. This doping dependence of the coupling strength induces a shift from the critical doping for the maximal value of the bare pair gap parameter to the optimal doping for the maximal value of the effective pair gap parameter, which leads to a difference between the optimal doping for the maximal Tc and the critical doping for the highest ρs.PACS numbers: 74.62. Dh, 74.20.Mn, 74.25.Bt, The parent compounds of cuprate superconductors are Mott insulators with an antiferromagnetic long-range order (AFLRO) 2 . However, this AFLRO is suppressed by doped charge carriers, then superconductivity arises from the binding of charge carriers into Cooper pairs 3 , thereby forming a superfluid with a superconducting (SC) energy gap∆(k) in the single-particle excitation spectrum. This energy gap is corresponding to the energy for breaking a Cooper pair of the charge carriers and creating two excited states 3 , while the superfluid density ρ s is proportional to the squared amplitude of the macroscopic wave function 4 , and therefore describes the SC charge carriers. In this case, both∆(k) and ρ s are thus two fundamental parameters whose variation as a function of doping and temperature provides important information crucial to understanding the details of the SC state 3-5 . After intensive investigations over more than two decades, some essential features of the evolution of the SC state in cuprate superconductors with doping have been experimentally established [5][6][7][8][9][10][11] : where the measured energy gap parameter∆ and the SC transition temperature T c show a domelike shape doping dependence, i.e., the maximal∆ and T c occur around the optimal doping δ optimal ≈ 0.15, and then decrease in both the underdoped and the overdoped regimes 6-8 . Moreover, the experimental measurements 9-11 throughout the SC dome show that the superfluid density ρ s appears from the starting point of the SC dome, and then increases with increasing doping in the lower doped regime. However, this ρ s reaches its highest value around the critical doping δ critical ≈ 0.19, and then decreases at the higher doped regime, eventually disappearing together with∆ at the end of the SC dome. In particular, it has been shown [5][6][7][8][9][10][11] that the maximal T c around the optimal doping and the peak of ρ s around the critical doping is a common feature of cuprate superconductors. Since∆ measures the strength of the binding o...

The interplay between the superconducting gap and normal-state pseudogap in cuprate superconductors is studied based on the kinetic energy driven superconducting mechanism. It is shown that the interaction between charge carriers and spins directly from the kinetic energy by exchanging spin excitations in the higher power of the doping concentration induces the normal-state pseudogap state in the particle-hole channel and superconducting state in the particle-particle channel, therefore there is a coexistence of the superconducting gap and normal-state pseudogap in the whole superconducting dome. This normal-state pseudogap is closely related to the quasiparticle coherent weight, and is a necessary ingredient for superconductivity in cuprate superconductors. In particular, both the normal-state pseudogap and superconducting gap are dominated by one energy scale, and they are the result of the strong electron correlation.Comment: 7 pages, 3 figures, added discussions and references, accepted for publication in Phys. Rev.