Related papers: Conductivity of underdoped YBa2Cu3O7-d : evidence …
The pseudogap (PG) derived from the analysis of the excess conductivity $\sigma'(T)$ in superlattices and double-layer films of $YBa_2Cu_3O_{7-\delta}$-$PrBa_2Cu_3O_{7-\delta}$(YBCO-PrBCO), prepared by pulsed laser deposition, is studied…
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)…
The complex conductivity of underdoped and optimally doped YBa$_2$Cu$_3$O$_{7-\delta}$ samples and overdoped similar compound Y$_{0.7}$Ca$_{0.3}$Ba$_2$Cu$_3$O$_{7-\delta}$ was measured using time-domain terahertz spectroscopy. In the normal…
Thermal transport in the T -> 0 limit was measured as a function of doping in high-quality single crystals of the cuprate superconductor YBa_2Cu_3O_y. The residual linear term kappa_0/T is found to decrease as one moves from the overdoped…
The investigation of the penetration depth \lambda_{ab}(T,p) in YBa_2Cu_3O_{7-x} crystals allowed to observe the following features of the superfluid density n_s(T,p)\propto \lambda_{ab}^{-2}(T,p) as a function of temperature T<Tc/2 and…
To investigate the relationship between the pseudogap and superconductivity, we measured both the in-plane ($\rho_{ab}$) and out-of-plane ($\rho_c$) resistivity for oxygen-controlled Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ single crystals…
We calculate the c-axis infrared conductivity $\sigma_c(\omega)$ in underdoped cuprate superconductors for spinfluctuation exchange scattering within the CuO$_2$-planes including a phenomenological d-wave pseudogap of amplitude $E_g$. For…
Temperature and doping dependent tunneling spectroscopy on $Bi_2Sr_2CaCu_2O_{8+\delta}$ single crystals has been investigated by using break-junction technique. The results provide direct evidence that the pseudogap persists into heavily…
The evolution of the temperature dependence of pseudogap $\Delta$*(T) in optimally doped (OD) YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) films with $T_{c}$ = 88.7 K under the influence of a magnetic field $B$ up to 8 T has been studied in detail.…
A combined study with use of time-domain pump-probe spectroscopy and time-domain terahertz transmission spectroscopy have been carried out on an underdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+{\delta}}$ thin film. It was observed that the low energy…
The optical properties of single crystals of YBa_2Cu_3O_{6+x} have been examined along the c axis above and below the critical temperature (T_c) for a wide range of oxygen dopings. The temperature dependence of the optically-determined…
Large pulsed magnetic fields up to 60 Tesla are used to suppress the contribution of superconducting fluctuations (SCF) to the ab-plane conductivity above Tc in a series of YBa2Cu3O(6+x). These experiments allow us to determine the field…
We report on measurements of the resistivity and Hall coefficient in underdoped GdBa2Cu3O7-d epitaxial thin films grown by off-axis magnetron sputtering. The films have been lithographically patterned allowing precise measurements of the…
The cuprate superconductors display several characteristic temperatures which decrease as the material composition is doped, tracing lines across the temperature-doping phase diagram. Foremost among these is the pseudogap transition. At a…
The strong coupling of superconductivity to the orthorhombic distortion in YBa2Cu3O7-d makes possible an analysis of the superconducting fluctuations without the necessity of subtracting any background. The present high-resolution…
Recent measurements on extremely-underdoped YBa2Cu3O6+y [Phys. Rev. Lett. 99, 237003 (2007)] have allowed the critical temperature (T_c), superfluid density [rho_0 (T << T_c)] and dc conductivity [sigma_dc (T ~ T_c)] to be determined for a…
Heat transport in the cuprate superconductors YBa$_2$Cu$_3$O$_{y}$ and La$_{2-x}$Sr$_x$CuO$_4$ was measured at low temperatures as a function of doping. A residual linear term kappa_{0}/T is observed throughout the superconducting region…
The in-plane resistivity has been measured in $La_{2-x}Sr_xCuO_4$ (LSxCO) superconducting thin films of underdoped ($x=0.10,0.12$), optimally-doped ($x=0.15$) and overdoped ($x=0.20,0.25$) compositions. These films were grown on…
Polarized and unpolarized triple-axis spectrometry has been used to study an underdoped YBa_2Cu3O6.6. Our results indicate that spin excitations in the superconducting state are essentially the same as those in the fully doped material…
The preformed-pairs theory of pseudogap physics in high-$T_C$ superconductors predicts a nonanalytic $T$-dependence for the $ab$-plane superfluid fraction, $\rho_S$, at low temperatures in underdoped cuprates. We report high-precision…