Related papers: Superconducting Gap and Pseudogap in Bi-2212
We report the observation of a pseudogap in the \emph{ab}-plane optical conductivity of underdoped Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$ ($x = 0.2$ and 0.12) single crystals. Both samples show prominent gaps opened by a spin density wave (SDW)…
Tunneling spectra are reported for Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} (Bi-2212) over a wide doping range using superconductor-insulator-superconductor (SIS) break junctions. The energy gap inferred from the tunneling data displays a…
Single crystalline Tl2Ba2Ca2Cu3O10 was studied using electronic Raman scattering. The renormalization of the scattering continuum was investigated as a function of the scattering geometry to determine the superconducting energy gap…
We show that the novel features observed in Raman experiments on optimally doped and underdoped Bi-2212 compounds in $B_{1g}$ geometry can be explained by a strong fermionic self-energy due to the interaction with spin fluctuations. We…
The superconducting gap Delta has been measured in Bi2Sr2-xLaxCuO6+d single crystals in a wide range of temperatures 4.2 K < T < Tc by point-contact and tunnelling spectroscopy for current in c-direction. The value of Delta(4.2 K) was found…
Ultrafast broadband transient reflectivity experiments are performed to study the interplay between the non-equilibrium dynamics of the pseudogap and the superconducting phases in Bi$_{2}$Sr$_{2}$Ca$_{0.92}$Y$_{0.08}$Cu$_{2}$O$_{8+\delta}$.…
For YBa_2Cu_3O_{6+\delta} and Bi_2Sr_2CaCu_2O_8 superconductors, electronic Raman scattering from high- and low-energy excitations has been studied in relation to the hole doping level, temperature, and energy of the incident photons. For…
We report the ultra-fast optical response of quasi-particles (QPs) in both the pseudogap (PG) and superconducting (SC) states of underdoped (UD) Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ (Bi2212) single crystal measured with the…
In this paper, we review some of our ARPES results on the superconducting and pseudo gaps in Bi2Sr2CaCu2O8+x. We find that optimally and overdoped samples exhibit a d-wave gap, which closes at the same temperature, Tc, for all k points. In…
Using polarization-resolved electronic Raman scattering we study under-doped, optimally-doped and over-doped Ba$_{1-x}$K$_{x}$Fe$_2$As$_2$ samples in the normal and superconducting states. We show that low-energy nematic fluctuations are…
Interlayer tunneling spectroscopy measurements were performed on mesa arrays of Bi-2212 single crystals, intercalated with HgBr$_2$. Tunneling conductances were obtained over a wide temperature range to examine the spectral features,…
We report Raman measurements on Bi2Sr2CaCu2O8+d single crystals which allow us to quantitavely evaluate the doping dependence of the density of Cooper pairs in the superconducting state. We show that the drastic loss of Cooper pairs in the…
Combining electronic Raman scattering experiments with cellular dynamical mean field theory, we present evidence of the pseudogap in the superconducting state of various hole-doped cuprates. In Bi2Sr2CaCu2O8+d we track the superconducting…
The momentum dependence of the superconducting gap in the cuprates has been debated, with most experiments reporting a deviation from a simple $d_{x^2-y^2}$ form in the underdoped regime and a few experiments claiming that a simple…
A phenomenological strong coupling model that has been used to analyze superconducting- insulator-superconducting (SIS) break junction experiments on optimal to overdoped Bi-2212 is modified to include a pseudogap. The calculated density of…
Application of a significantly large bias voltage to small Bi2Sr2CaCu2O8+x mesa structures leads to persistent doping of the mesas. Here we employ this effect for analysis of the doping dependence of the electronic spectra of Bi-2212 single…
We use novel STM techniques in concert to study the doping dependence of electronic structure in Bi-2212. At all dopings, the low energy states are relatively homogenous except for dispersive density-of-states modulations whose properties…
We express the superconducting gap, $\Delta(T)$, in terms of thermodynamic functions in both $s$- and d-wave symmetries. Applying to Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ and Y$_{0.8}$Ca$_{0.2}$Ba$_2$Cu$_3$O$_{7-\delta}$ we find that for all…
Recent Raman scattering data in B_{1g} and B_{2g} geometries in the superconducting state of underdoped cuprates were interpreted as evidence for two distinct energy gaps. We argue that these data can be equally well explained within a one…
Electronic Raman scattering from high- and low-energy excitations was studied as a function of temperature, extent of hole doping, and energy of the incident photons in Bi_2Sr_2CaCu_2O_{8 \pm \delta} superconductors. For underdoped…