Charge order driven by Fermi-arc instability and its connection with pseudogap in cuprate superconductors

The recently discovered charge order is a generic feature of cuprate superconductors, however, its microscopic origin remains debated. Within the framework of the fermion-spin theory, the nature of charge order in the pseudogap phase and its evolution with doping are studied by taking into account the electron self-energy (then the pseudogap) effect. It is shown that the antinodal region of the electron Fermi surface is suppressed by the electron self-energy, and then the low-energy electron excitations occupy the disconnected Fermi arcs located around the nodal region. In particular, the charge-order state is driven by the Fermi-arc instability, with a characteristic wave vector corresponding to the hot spots of the Fermi arcs rather than the antinodal nesting vector. Moreover, although the Fermi arc increases its length as a function of doping, the charge-order wave vector reduces almost linearity with the increase of doping. The theory also indicates that the Fermi arc, charge order, and pseudogap in cuprate superconductors are intimately related each other, and all of them emanates from the electron self-energy due to the interaction between electrons by the exchange of spin excitations.Comment: 10 pages, 8 figures, added comments and reference, accepted for publication in Philosophical Magazine. arXiv admin note: text overlap with arXiv:1502.0290

Doping dependence of Meissner effect in cuprate superconductors

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

Doping dependence of electromagnetic response in electron-doped cuprate superconductors

Within the framework of the kinetic energy driven superconducting mechanism, the doping dependence of the electromagnetic response in the electron-doped cuprate superconductors is studied. It is shown that although there is an electron-hole asymmetry in the phase diagram, the electromagnetic response in the electron-doped cuprate superconductors is similar to that observed in the hole-doped cuprate superconductors. The superfluid density depends linearly on temperature, except for the strong deviation from the linear characteristics at the extremely low temperatures.Comment: 6 pages, 2 figure

Why there is a difference between optimal doping for maximal Tc and critical doping for highest \rho_s in cuprate superconductors?

A long-standing puzzle is why there is a difference between the optimal doping \delta_{optimal}=0.15 for the maximal superconducting (SC) transition temperature Tc and the critical doping \delta_{critical}=0.19 for the highest superfluid density \rho_s 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, \rho_s 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 \rho_s.Comment: 5 pages, 4 figure

Correlation between charge order and second-neighbor hopping in cuprate superconductors

The correlation between the charge-order wave vector Q_{CD} and second-neighbor hopping t' in cuprate superconductors is studied based on the t-t'-J model. It is shown that the magnitude of the charge-order wave vector Q_{CD} increases with the increase of t', and then the experimentally observed differences of the magnitudes of the charge-order wave vector Q_{CD} among the different families of cuprate superconductors at the same doping concentration can be attributed to the different values of t'.Comment: 5 pages, 3 figures, accepted for publication in the special issue of Journal of Superconductivity and Novel Magnetism for the International Conference of superstripes 201

Doping dependence of thermodynamic properties in cuprate superconductors

The doping and temperature dependence of the thermodynamic properties in cuprate superconductors is studied based on the kinetic energy driven superconducting mechanism. By considering the interplay between the superconducting gap and normal-state pseudogap, the some main features of the doping and temperature dependence of the specific-heat, the condensation energy, and the upper critical field are well reproduced. In particular, it is shown that in analogy to the domelike shape of the doping dependence of the superconducting transition temperature, the maximal upper critical field occurs around the optimal doping, and then decreases in both underdoped and overdoped regimes. Our results also show that the humplike anomaly of the specific-heat near superconducting transition temperature in the underdoped regime can be attributed to the emergence of the normal-state pseudogap in cuprate superconductors.Comment: 8 pages, 7 figures, typos corrected and added reference, accepted for publication in Physica

Pseudogap-induced asymmetric tunneling in cuprate superconductors

The asymmetric tunneling in cuprate superconductors is studied based on the kinetic energy driven superconducting mechanism. By taking into account the interplay between the superconducting gap and normal-state pseudogap, the essential feature of the evolution of the asymmetric tunneling with doping and temperature is qualitatively reproduced. In particular, the asymmetry of the tunneling spectrum in the underdoped regime weakens with increasing doping, and then the symmetric tunneling spectrum recovers in the heavily overdoped regime. The theory also shows that the asymmetric tunneling is a natural consequence due to the presence of the normal-state pseudogap.Comment: 6 pages, 4 figures, added discussions and references, accepted for publication in Physica

Magnetic field induced reduction of the low-temperature superfluid density in cuprate superconductors

The weak magnetic field induced reduction of the low-temperature superfluid density in cuprate superconductors is studied based on the kinetic energy driven superconducting mechanism. The electromagnetic response kernel is evaluated by considering both couplings of the electron charge and electron magnetic momentum with a weak magnetic field and employed to calculate the superfluid density, then the main features of the weak magnetic field induced reduction of the low-temperature superfluid density are well reproduced. The theory also shows that the striking behavior of the weak magnetic field induced reduction of the low-temperature superfluid density is intriguingly related to both depairing due to the Pauli spin polarization and nonlocal response in the vicinity of the d-wave gap nodes on the Fermi surface to a weak magnetic field.Comment: 7 pages, 3 figures, added discussions and references, accepted for publication in Phys. Rev.

Electronic structure of cuprate superconductors in a full charge-spin recombination scheme

A long-standing unsolved problem is how a microscopic theory of superconductivity in cuprate superconductors based on the charge-spin separation can produce a large electron Fermi surface. Within the framework of the kinetic-energy driven superconducting mechanism, a full charge-spin recombination scheme is developed to fully recombine a charge carrier and a localized spin into a electron, and then is employed to study the electronic structure of cuprate superconductors in the superconducting-state. In particular, it is shown that the underlying electron Fermi surface fulfills Luttinger's theorem, while the superconducting coherence of the low-energy quasiparticle excitations is qualitatively described by the standard d-wave Bardeen-Cooper-Schrieffer formalism. The theory also shows that the observed peak-dip-hump structure in the electron spectrum and Fermi arc behavior in the underdoped regime are mainly caused by the strong energy and momentum dependence of the electron self-energy.Comment: 14 pages, 7 figures. Updated references, accepted for publication in Physica C. arXiv admin note: text overlap with arXiv:1501.0242

Periodicity of the giant vortex states in mesoscopic superconducting rings

The giant vortex states of a multiply connected superconductor, with radius comparable to the penetration depth and the coherence length, are theoretically investigated based on the nonlinear Ginzburg-Landau theory, in which the induced magnetic field by the super-currents is accurately taken into account. The solutions of Ginzburg-Landau equations are found to be actually independent of the angular momentum L in a gauge invariant point of view, provided that the hole is in the center. Different cases with the paramagnetic current, the diamagnetic current, and the coexistence of the above two, have been studied numerically. The interpretation of the L-independent solutions of Ginzburg-Landau equations is given based on the same principle of Aharonov-Bohm effect, and could be observed by Little-Parks like oscillations near the phase boundary.Comment: 4 figure