Related papers: Carrier doping in Pr_{1+x}Ba_{2-x}Cu_3O_7 studied …
The electron-doped cuprates Pr_{2-x}Ce_xCuO_4 and Nd_{2-x}Ce_xCuO_4 have been studied by electronic Raman spectroscopy across the entire region of the superconducting (SC) phase diagram. The SC pairing strength is found to be consistent…
We investigated the charge distribution in Pr_{1+x}Ba_{2-x}Cu_3O_{6+y}-crystals at liquid-He temperature by means of ^{63,65}Cu- and ^{141}Pr-NMR and NQR. The electric field gradients determined for the different oxygen coordinations of…
First principles investigations of the high temperature superconducting system Ba$_2$CuO$_{3+\delta}$, recently discovered at $\delta\approx0.2$ at $T_c=70$ K, are applied to demonstrate the effects of oxygen ordering on the electronic and…
Transport properties of Nd$_{2-x}$Ce$_x$CuO$_{4+\delta}$ single crystal films are investigated in magnetic fields $B$ up to 9T at $T$=(0.4-4.2)K. An analysis of normal state (at $B>B_{c2}$) Hall coefficient $R_H$$^n$ dependence on Ce doping…
We measured the temperature dependence of the in-plane polarized reflectivity spectra of twin-free Y$_{1-x}$Ca$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-{\delta}}$ single crystals with different Ca-concentrations (x=0,0.11 and 0.16) from optimally doped…
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…
The magnetic phase diagrams, and other physical characteristics, of the hole- doped {\em La$_{2-x}$Sr$_x$CuO$_4$} and electron-doped {\em Nd$_{2-x}$Ce$_x$ CuO$_4$} high-temperature superconductors are profoundly different. Starting with the…
We present a systematic study of the perovskite-related system La2-xSrxCu1-yRuyO4 using Cu-L2,3, Ru-L2,3, and O-K x-ray absorption spectroscopy (XAS). This system can be regarded as a solid solution of the two superconductors La2-xSrxCuO4…
We present a valence transition model for electron- and hole-doped cuprates, within which there occurs a discrete jump in ionicity Cu$^{2+} \to$ Cu$^{1+}$ upon doping, at or near optimal doping in the electron-doped compounds and at the…
We synthesized a series of Nb$_{2}$Pd$_{1-x}$Ru$_{x}$S$_{5}$ polycrystalline samples by a solid-state reaction method and systematically investigated the Ru-doping effect on superconductivity by transport and magnetic measurements. It is…
In this study, we perform a numerical simulation on the recently discovered high-temperature superconductor ($T_c$= 73K) Ba$_2$CuO$_{3.2}$ \cite{lietal} while focusing on doping dependence of alternating CuO$_6$ octahedra and CuO chain-like…
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 Cu-NMR/NQR and F-NMR studies on the multilayered high-T_c copper oxides Ba_2Ca_{n-1}Cu_nO_{2n}F_2 with n=2,3,4, where n is the number of CuO_2 planes. It is revealed that bi-layered Ba_2CaCu_2O_4F_2 is an underdoped superconductor…
We have successfully grown the single crystal of a low carrier density system Y$_3$Ru$_4$Ge$_{13}$ which crystallizes in the cubic crystal structure with the space group Pm3n. Y$_3$Ru$_4$Ge$_{13}$ exhibits super conductivity below 2.85 K as…
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…
All previous cuprate superconductors display a set of common features: (i) vicinity to a Cu 3$d^{9}$ configuration; (ii) separated CuO$_2$ planes; (iii) superconductivity for doping $\delta \sim$ 0.1$-$0.3. Recently [PNAS {\bf 24}, 12156…
Thus far, there is no cuprate system where both n-type and p-type charge carriers can be doped without changing the crystallographic structure. For studying the electron-hole symmetry in an identical structure, we try to dope n-type…
We report hole-doping dependence of the in-plane resistivity \rho_{ab} in a cuprate superconductor La_{2-x}Sr_{x}CuO_{4}, carefully examined using a series of high-quality single crystals. Our detailed measurements find a tendency towards…
The recently discovered cuprate superconductor Ba$_2$CuO$_{3+\delta}$ exhibits a high $T_c\simeq73$K at $\delta\simeq0.2$. The polycrystal grown under high pressure has a structure similar to La$_2$CuO$_4$, but with dramatically different…
We present a single crystal Cu NMR study of the cuprate superconductor La$_{2-x}$Sr$_{x}$CuO$_4$ with hole doping levels between $x=2$\% and $8$\%. Measurements with short spin echo times enable us to systematically study the local…