相关论文: Time- and Momentum-resolved Gap Dynamics in Bi2Sr2…

We use angle-resolved photoemission spectroscopy and full-potential linearized augmented-plane-wave (FP-LAPW) calculations to study the electronic structure of BaCo2As2. The Fermi surface (FS) maps and the corresponding band dispersion data…

We consider a model for bilayer superconductors where an interlayer pairing amplitude $\Delta_\perp$ co-exists with intralayer pairing $\Delta_\|$ of $d_{x^2 - y^2}$ symmetry. This model is motivated by a recent photoemission experiment…

We discuss polarization selection rules for angle-resolved photoemission spectroscopy in Bi2212. Using these we show that the ``hump'' in the superconducting gap observed in the $X$ quadrant in our earlier work is not on the main $CuO_2$…

We analyze the anomalies of superconducting state within a simple exactly solvable model of the pseudogap state, induced by fluctuations of ``dielectric'' short range order, for the model of the Fermi surface with ``hot'' patches. The…

We studied the far-infrared reflectance of superconducting MgB2 in and out of equilibrium using pulsed synchrotron radiation. The equilibrium data can be described by a single energy gap at 2 Delta / hc = 43 cm-1. The fit improves slightly…

High-$T_c$ cuprate superconductors are characterized by a strong momentum-dependent anisotropy between the low energy excitations along the Brillouin zone diagonal (nodal direction) and those along the Brillouin zone face (antinodal…

The maximum value of the energy gap $\Delta\simeq 8\ meV$ and the ratio $2\delta/kT_c\simeq~2.5$ are determined for a high-temperature superconductor $\rm Bi_2Sr_2CaCu_2O_{8+y}$ by using point contacts. It was found that the…

The interplay between superconductivity and the pseudogap is an important aspect of cuprate physics. However, the nature of the pseudogap remains controversial, in part because different experiments have suggested different gap functions.…

Here we report extensive ultrafast time-resolved reflectivity experiments on overdoped Bi$_{2}$Sr$_{2}$Ca$_{1-x}$Y$_x$Cu$_{2}$O$_{8+\delta}$ single crystals (T$_C$=78 K) aimed to clarify the nature of the superconducting-to-normal-state…

The nature of the pseudogap state, observed above the superconducting transition temperature TC in many high temperature superconductors, is the center of much debate. Recently, this discussion has focused on the number of energy gaps in…

We performed an optical spectroscopy measurement on single crystals of $\mathrm{Ba_2Ti_2Fe_2As_4O}$, which is a newly discovered superconductor showing a coexistence of superconductivity and density wave order. The study reveals a spectral…

The results of a previous work, where it was considered the effect of hole doping on a simple model of the CuO2 planes in La2CuO4, are extended. The parameters are adjusted with the objective to fix the known values of the gap of 2 eV for…

We study optimally doped Bi$_{2}$Sr$_{2}$Ca$_{0.92}$Y$_{0.08}$Cu$_{2}$O$_{8+\delta}$ (Bi2212) using angle-resolved two-photon photoemission spectroscopy. Three spectral features are resolved near 1.5, 2.7, and 3.6 eV above the Fermi level.…

In high-temperature superconductivity, the process that leads to the formation of Cooper pairs, the fundamental charge carriers in any superconductor, remains mysterious. We use a femtosecond laser pump pulse to perturb superconducting…

Using an energy-momentum dispersion for Bi2Sr2CaCu2O8 obtained from angle-resolved photoelectron spectroscopy we show that the shrinking Fermi arc model of the pseudogap is inconsistent with Raman scattering below Tc and specific heat near…

The electronic structure of the new superconductor, SmO$_{1-x}$F$_x$FeAs ($x=0.15$), has been studied by angle-integrated photoemission spectroscopy. Our data show a sharp feature very close to the Fermi energy, and a relative flat…

The superconducting state is achieved by the condensation of Cooper pairs and is protected by the superconducting gap. The pairing interaction between the two electrons of a Cooper pair determines the superconducting gap function. Thus, it…

The relationship between the pseudogap and superconductivity remains a central puzzle in the physics of cuprates. Hydrostatic pressure provides a clean tuning parameter free from chemical disorder, yet probing the microscopic energy scales…

We observed the anisotropic superconducting-gap (SC-gap) structure of a slightly overdoped superconductor, Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ ($x=0.1$), using three-dimensional (3D) angle-resolved photoemission spectroscopy. Two hole…

We use angle-resolved photoemission spectroscopy (ARPES) to investigate the properties of the energy gap(s) in optimally doped (Bi,Pb)2(Sr,La)2CuO6+d (Bi2201). We find that the spectral gap has two components in the superconducting state: a…