[en] When the Mott insulating state is suppressed by charge carrier doping, the pseudogap phenomenon emerges, where at the low-temperature limit, superconductivity coexists with some ordered electronic states. Within the framework of the kinetic-energy–driven superconductivity, the nature of the pair-density-wave order in cuprate superconductors is studied by taking into account the pseudogap effect. It is shown that the onset of the pair-density-wave order does not produce an ordered gap, but rather a novel hidden order as a result of the interplay of the charge-density-wave order with superconductivity. As a consequence, this novel hidden pair-density-wave order as a subsidiary order parameter coexists with the charge-density-wave order in the superconducting state, and is absent from the normal state.

[en] The angle-resolved photoemission spectroscopy (ARPES) autocorrelation in the electron-doped cuprate superconductors is studied based on the kinetic energy–driven superconducting (SC) mechanism. It is shown that the strong electron correlation induces the electron Fermi surface (EFS) reconstruction, where the most of the quasiparticles locate at around the hot spots on EFS, and then, these hot spots connected by the scattering wave vectors q_i construct an octet scattering model. In a striking analogy to the hole-doped case, the sharp ARPES autocorrelation peaks are directly correlated with the scattering wave vectors q_i and are weakly dispersive in momentum space. However, in a clear contrast to the hole-doped counterparts, the position of the ARPES autocorrelation peaks moves toward to the opposite direction with the increase of doping. The theory also indicates that there is an intrinsic connection between the ARPES autocorrelation and quasiparticle scattering interference (QSI) in the electron-doped cuprate superconductors.