相关论文: Suppression and restoration of superconductivity i…
We argue that an effective single-particle model to explain the destructive role of Pr on superconductivity in PrBa$_2$Cu$_3$O$_7$, is inconsistent with the experimental ac conductivity in that compound.
Recent reports about observations of superconductivity in PrBa2Cu3O7 raise a number of questions: (i) of various theories striving to explain the Tc suppression in PrxY{1-x}Ba2Cu3O7, are there any compatible with possible superconductivity…
Recent experiments by Mertz et al (Phys. Rev. B55, 9160, 1997) demonstrated that the loss of superconductivity upon Pr doping is associated with the change of the character of the oxygen holes from $p_{\sigma}$ to $p_{\pi}.$ This experiment…
We report superconductivity with $T_{c,onset}$=$\sim$10K in Pr$_{2}$Ba$_{4}$Cu$_{7}$O$_{15-\delta}$ compound possessing metallic double chains. A reduction treatment on as-sintered samples causes not only the enhanced metallic conduction…
The mechanism behind superconductivity suppression induced by Pr substitutions in YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) has been a mystery since its discovery: in spite of being isovalent to Y$^{3+}$ with a small magnetic moment, it is the…
We have measured the picosecond conductivity dynamics in Y1-xPrxBa2Cu3O7 thin films from 0.3-2.0 terahertz. Our experimental technique measures the complex conductivity $\sigma_{re}(\omega$) + i$\sigma_{im}(\omega$) permitting the…
The (mostly) insulating behaviour of PrBa2Cu3O7-d is still unexplained and even more interesting since the occasional appearance of superconductivity in this material. Since YBa2Cu3O7-d is nominally iso-structural and always…
We present studies of the thermal, magnetic and electrical transport properties of reduced polycrystalline Pr_2Ba_4Cu_7O_{15-\delta} (Pr247) showing a superconducting transition at Tc = 10 - 16 K and compare them with those of as-sintered…
We report on measurements on Y1-xPrxBa2Cu3O7-delta single crystals, with x varying from 0 to 2.4%. The upper and the lower critical fields, Hc2 and Hc1, the Ginzburg-Landau parameter and the critical current density, Jc(B), were determined…
In PrBa_2Cu_3O_{7-y} (Pr123) single crystals grown by the flux method the kink in the magnetic susceptibility chi_{ab}(T), connected with AFM ordering of Pr, disappears after field cooling (FC) in a field H||ab-plane whereas the kink in…
We present a low-energy muon-spin-rotation study of the magnetic and superconducting properties of YBa2Cu3O7/PrBa2Cu3O7 trilayer and bilayer heterostructures. By determining the magnetic-field profiles throughout these structures we show…
The mechanism of superconductivity in Pr$_2$Ba$_4$Cu$_7$O$_{15-\delta}$ is studied using a quasi-one dimensional double chain model with appopriate hopping integrals, on-site $U$, and off-site repulsion $V_1$. Applying the fluctuation…
Superconducting and structural phase transitions in a pyrochlore oxide Cd2Re2O7 are studied under high pressure by x-ray diffraction and electrical resistivity measurements. A rich P-T phase diagram is obtained, which contains at least two…
The coupling between the superconducting planes of YBa2Cu3O{7-\delta}/ PrBa2Cu3O{7-\delta} superlattices has been measured by c-axis transport. We show that only by changing the thickness of the superconducting YBa2Cu3O{7-\delta} layers, it…
We have measured the electrodynamic properties of Y_{1-x}Pr_xBa_2Cu_3O_7 single crystal thin films as a function of temperature using coherent THz-time-domain spectroscopy. We obtain directly the complex conductivity…
Bulk superconductor samples of YBa2Cu3-xCoxO7-{\delta} with x = 0, 0.01, 0.03, 0.05 are synthesized by solid-state reaction route. Both x-ray diffraction and electron microscopy have been employed to study the phase identification,…
In contrast to the "Pr-issue" that neither PrBa2Cu3O7 (Pr123) nor PrBa2Cu4O8 (Pr124) shows superconductivity (SC), we have observed 100%-fraction of SC in an oxygen-reduced Pr2Ba4Cu7O(15-delta) (Pr247) which has a hybrid structure that…
Most of the novel superconductors are uniaxial crystals, with metallic planes ($ab$) orthogonal to an insulating axis ($c$). Far-infrared measurements of the reflectivity $R_{ab} (\omega)$ provide valuable information on their low-energy…
The suppression of superconductivity by substitution effects has been measured in high quality single crystals of U(Pt_{1-x} Pd_x)_3 with 0 <= x <= 0.002. While the superconducting transition temperature T_c varies linearly with residual…
Superconductivity in thin films and powders, and in single crystals of Pr-123 has been found by Blackstead et al. and Zou et al., respectively. Nevertheless, up to now it has never been reported in sintered-policrystalline samples. We have…