Non-Universal Pairing Symmetry and Pseudogap Phenomena in Hole- and Electron-Doped Cuprate Superconductors (original) (raw)
Related papers
Evolution of Pairing Orders between Pseudogap and Superconducting Phases of Cuprate Superconductors
Scientific Reports, 2019
One of the most puzzling problems of high temperature cuprate superconductor is the pseudogap phase (pG) at temperatures above the superconducting transition temperature in the underdoped regime. the pG phase is found by the angle-resolved photoemission spectra (ARpes) to have a gap at some regions in momentum space and a fraction of Fermi surface remained, known as Fermi arcs. The arc turns into a d-wave SC gap with a node below the SC transition temperature. Here, by studying a strongly correlated model at low temperatures, we obtained a phase characterized by two kinds of pairing order parameters with the total momentum of the Cooper pair to be zero and finite. The finite momentum pairing is accompanied with a spatial modulation of pairing order, i.e. a pair density wave (pDW). these pDW phases are intertwined with modulations of charge density and intra-unit cell form factors. The coexistence of the two different pairing orders provides the unique two-gaps like spectra observed by ARPES for superconducting cuprates. As temperature raises, the zero-momentum pairing order vanishes while the finite momentum pairing orders are kept, thus Fermi arcs are realized. The calculated quasiparticle spectra have the similar doping and temperature dependence as reported by ARPES and scanning tunneling spectroscopy (STS). The consequence of breaking symmetry between x and y due to the unidirectional pDW and the possibility to probe such a pDW state in the pG phase is discussed.
2004
We investigate the issues of competing orders and quantum criticality in cuprate superconductors via experimental studies of the high-field thermodynamic phase diagrams and the quasiparticle tunneling spectroscopy. Substantial field-induced quantum fluctuations are found in all cuprates investigated, and the corresponding correlation with quasiparticle spectra suggest that both electron-(n-type) and hole-doped (p-type) cuprate superconductors are in close proximity to a quantum critical point that separates a pure superconducting (SC) phase from a phase consisting of coexisting SC and a competing order. We further suggests that the relevant competing order is likely a spin-density wave (SDW) or a charge density wave (CDW), which can couple efficiently to an in-plane Cu-O bond stretching longitudinal optical (LO) phonon mode in the p-type cuprates but not in the n-type cuprates. This cooperative interaction may account for the pseudogap phenomenon above T c only in the p-type cuprate superconductors.
Physica C: Superconductivity, 2008
The low-energy quasiparticle excitations in hole-and electron-type cuprate superconductors are investigated via both experimental and theoretical means. It is found that the doping and momentum dependence of the empirical low-energy quasiparticle excitations is consistent with a scenario of coexisting competing orders and superconductivity in the ground state of the cuprates. This finding, based on zero-field quasiparticle spectra, is further corrobarated by the spatially resolved vortex-state scanning tunneling spectroscopy, which reveals pseudogap-like features consistent with a remaining competing order inside the vortex core upon the suppression of superconductivity. The competing orders compatible with empirical observations include the charge-density wave and spin-density wave. In contrast, spectral characteristics derived from incorporating the d-density wave as a competing order appear unfavorable in comparison with experiments.
Scanning Tunneling Spectroscopic Studies of the Pairing State of Cuprate Superconductors
2003
Quasiparticle tunneling spectra of both hole-doped (p-type) and electron-doped (n-type) cuprates are studied using a low-temperature scanning tunneling microscope. The results reveal that neither the pairing symmetry nor the pseudogap phenomenon is universal among all cuprates, and that the response of n-type cuprates to quantum impurities is drastically different from that of the p-type cuprates. The only ubiquitous features among
Electronic structure of the electron-doped cuprate superconductors
Physics Letters A, 2007
Within the framework of the kinetic energy driven d-wave superconductivity, the electronic structure of the electron doped cuprate superconductors is studied. It is shown that although there is an electron-hole asymmetry in the phase diagram, the electronic structure of the electron-doped cuprates in the superconducting-state is similar to that in the hole-doped case. With increasing the electron doping, the spectral weight in the [π, 0] point increases, while the position of the superconducting quasiparticle peak is shifted towards the Fermi energy. In analogy to the hole-doped case, the superconducting quasiparticles around the [π, 0] point disperse very weakly with momentum.
Superconductivity in electron-doped cuprates: Gap shape change and symmetry crossover with doping
Physical Review B, 2004
The Kohn-Luttinger mechanism for superconductivity is investigated in a model for the electron doped cuprates. The symmetry of the order parameter of the superconducting phase is determined as a function of the geometry of the Fermi surface together with the structure of the electron-hole susceptibility. It is found to remain d x 2 −y 2 wave within a large doping range. The shape of the gap anisotropy evolves with doping, with the maximum gap moving away from (π, 0), in good agreement with recent experiments. As the shift of the maximum increases, a crossover to dxy-symmetry is found.
Superconductivity and spin gaps in a class of cuprates
Physica B, 1994
A homologous series of cuprates, Sr n-1 Cu n+1 O 2 n formed by introducing a parallel array of planar defects into the infinite layer cuprate SrCuO 2, have been reported by Hiroi, Takano et al. In each CuO 2 plane, line defects consisting of CuO double chains result. An analysis of the electronic properties of such planes demonstrates that the stoichiometric compounds with n = 3,7,11,… will be frustrated quantum antiferromagnets and spin liquids. When lightly doped with holes, the spin gap will remain and singlet superconductivity should occur on a separate but high-temperature scale. This prediction may shed new light on the origin of the separate energy scales for the spin gap and superconductivity in other lightly doped cuprates.
Magnetic mechanism of quasiparticle pairing in hole-doped cuprate superconductors
Physical Review B, 2008
We have computed α 2 F 's for the hole-doped cuprates within the framework of the one-band Hubbard model, where the full magnetic response of the system is treated properly. The d-wave pairing weight α 2 F d is found to contain not only a low energy peak due to excitations near (π, π) expected from neutron scattering data, but to also display substantial spectral weight at higher energies due to contributions from other parts of the Brillouin zone as well as pairbreaking ferromagnetic excitations at low energies. The resulting solutions of the Eliashberg equations yield transition temperatures and gaps comparable to the experimentally observed values, suggesting that magnetic excitations of both high and low energies play an important role in providing the pairing glue in the cuprates.
Solid State Communications, 2007
We investigate the low-energy quasiparticle excitation spectra of cuprate superconductors by incorporating both superconductivity (SC) and competing orders (CO) in the bare Green's function and quantum phase fluctuations in the proper self-energy. Our approach provides consistent explanations for various empirical observations, including the excess subgap quasiparticle density of states, "dichotomy" in the momentum-dependent quasiparticle coherence and the temperature-dependent gap evolution, and the presence (absence) of the low-energy pseudogap in hole-(electron-) type cuprates depending on the relative scale of the CO and SC energy gaps.
Unveiling the nature of the pseudogap and its relation to both superconductivity and antiferromagnetic Mott insulators, the pairing mechanism, and a non-Fermi liquid phase is a key issue for understanding high temperature superconductivity in cuprates.We here show that antiparallel magnetic order can be reasonably and naturally predicted in hole-doped CuO2 planes by starting from the ground state of a weakly doped antiferromagnetic insulator, where a Skyrmion-type three-dimensional spin texture is created around the doped hole. The superconducting transition temperature Tc can be understood in terms of the temperature at which long-range antiparallel magnetic ordering is established, resulting in the magnetically mediated superconducting state with phase-coherent Cooper pairs. Upon heating above Tc, long-range phase coherence in the pair state is lost, but the pair condensate still survives on the medium-range length scale, transforming to the pseudogap state with charge and magneti...