Related papers: a-b Plane Anisotropy in YBCO
We measured the in-plane resistivity anisotropy in the underdoped Ca$_{1-x}$Na$_x$Fe$_2$As$_2$ single crystals. The anisotropy (indicated by $\rho_{\rm b} - \rho_{\rm a}$) appears below a temperature well above magnetic transition…
We formulate a model describing the doping ($x$) and temperature ($T$) dependence of the $ab$-plane and c-axis penetration depth of a cuprate superconductor. The model incorporates the suppression of the superfluid density with underdoping…
To clarify the order parameter symmetry of cuprates, the magnetic penetration depth $\lambda$ was measured along the crystallographic directions $a$, $b$, and $c$ in single crystals of YBa$_2$Cu$_4$O$_8$ via muon spin rotation. This method…
We study the effects of anisotropic order parameters on the temperature dependence of London penetration depth anisotropy $\gamma_\lambda(T)$. After MgB$_2$, this dependence is commonly attributed to distinct gaps on multi-band Fermi…
We study theoretically the chain and in-plane optical conductivities of detwinned YBa$_2$Cu$_3$O$_{y}$. We elaborate that the chain is superconducting for $y>6.67$ while insulating for $y<6.67$ due to the competition between the plane-chain…
Measurement of the penetration depth as a function of temperature using millimeter wave transmission in the range 130-500GHz are reported for three YBCO thin films. The experiment provides the absolute value for the penetration depth at low…
Analysis of the a-b plane optical conductivity $\sigma_{ab}$ for both twinned and untwinned YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ as a function of temperature and doping shows that below a well defined temperature T*, a dip in the spectrum…
The effects of chain disorder on superconductivity in YBa_2Cu_3O_{7-\delta} are discussed within the context of a proximity model. Chain disorder causes both pair-breaking and localization. The hybridization of chain and plane wavefunctions…
A detailed inelastic neutron scattering study of the in-plane anisotropy of magnetic excitations in twin-free YBa$_2$Cu$_3$O$_{6.6}$ ($T_c =$ 61 K) reveals that the spin excitation spectra in the superconducting and normal states are…
We present measurements of the magnetic field dependence of the penetration depth Lambda(H) for untwinned YBa_2Cu_3O_6.95 for temperatures from 1.2 to 70 K in dc fields up to 42 gauss and directions 0, 45 and 90 degrees with respect to the…
Motivated by predictions of a substantial contribution of the "buckling" vibration of the CuO2 layers to d-wave superconductivity in the cuprates, we have performed an inelastic neutron scattering study of this phonon in an array of…
The interplay between the quasi 1-dimensional CuO-chains and the 2-dimensional CuO2 planes of YBa2Cu3O6+x (YBCO) has been in focus for a long time. Although the CuO-chains are known to be important as charge reservoirs that enable…
Following the work of Abrikosov and Gor'kov on the pair-breaking effects, one can derive the temperature dependencies of the electronic specific heat $C_s/T=\gamma^\prime+\mu T^2$ (with the jump at the superconducting transition $\Delta C…
The nature of the pseudogap phase is a central problem in the quest to understand high-Tc cuprate superconductors. A fundamental question is what symmetries are broken when that phase sets in below a temperature T*. There is evidence from…
We present a novel approach to the analysis of the normal state in-plane $\sigma_{ab}$ and out-of-plane $\sigma_{c}$ conductivities of anisotropic layered crystals such as oxygen deficient $YBa_{2}Cu_{3}O_{x}$. It can be shown that the…
The polarized femtosecond spectroscopies obtained from well characterized (100) and (110) YBa2Cu3O7-\delta thin films are reported. This bulk-sensitive spectroscopy, combining with the well-textured samples, serves as an effective probe to…
YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) has favorable macroscopic superconducting properties of $T_\mathrm{c}$ up to 93 K and $H_{c2}$ up to 150 T. However, its nanoscale electronic structure remains mysterious because bulk-like electronic…
The low temperature behaviour of the in-plane and c-axis conductivity of electron-doped cuprates like NCCO is examined; it is shown to be consistent with an isotropic quasiparticle scattering rate and an anisotropic interlayer hopping…
The temperature and angle dependent resistivity of Ba(Fe$_{0.75}$Ru$_{0.25}$)$_2$As$_2$ single crystals were measured in magnetic fields up to 14 T. The temperature dependent resistivity with the magnetic field aligned parallel to c-axis…
A scan of the superconductor -- nonsuperconductor transformation in single crystals YBa_2Cu_3O_{6+x} (x about 0.37) was done in two alternative ways, namely, by applying the magnetic field and by reducing the hole concentration through the…