electron-doped superconducting

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morozov
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electron-doped superconducting

Номер сообщения:#1   morozov » Вт фев 07, 2006 16:18

Role of oxygen in the electron-doped superconducting cuprates
Authors: J. S. Higgins, Y. Dagan, M. C. Barr, B. D. Weaver, R. L. Greene
Comments: 5 pages, 5 figures
Subj-class: Superconductivity

We report on resistivity and Hall measurements in thin films of the electron-doped superconducting cuprate Pr$_{2-x}$Ce$_{x}$CuO$_{4\pm\delta}$. Comparisons between x = 0.17 samples subjected to either ion-irradiation or oxygenation demonstrate that changing the oxygen content has two separable effects: 1) a doping effect similar to that of cerium, and 2) a disorder effect. These results are consistent with prior speculations that apical oxygen removal is necessary to achieve superconductivity in this compound.
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http://xxx.lanl.gov/pdf/cond-mat/0602142
С уважением, Морозов Валерий Борисович

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Номер сообщения:#2   morozov » Вт фев 14, 2006 17:32

Doping of Ce in T-La2CuO4: Rigorous test for electron-hole symmetry for high-Tc superconductivity
Authors: A. Tsukada, H. Yamamoto, M. Naito
Comments: 21 pages, 11 figures, submitted to Phys. Rev. B
Subj-class: Superconductivity

We report that Ce doping was achieved in La2CuO4 with the K2NiF4 (T) structure for the first time by molecular beam epitaxy. A synthesis temperature of as low as ~ 630C and an appropriate substrate choice, i.e., (001)LaSrGaO4 (a \~ 3.843 A), enebled us to incorporate Ce into K2NiF4 lattice and to obtain Ce-doped T-La2-xCexCuO4 up to x ~ 0.06. The doping of Ce makes T-La2CuO4 more insulating, which is in sharp contrast to Sr (or Ba) doping in T-La2CuO4, which make the compound metallic and superconducting. The observed smooth increase in resistivity from the hole-doped side (T-La2-xSrxCuO4) to the electron-doped side (T-La2-xCexCuO4) indicates that the electron-hole symmetry is broken in the T-phase materials.
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http://xxx.lanl.gov/pdf/cond-mat/0602303
С уважением, Морозов Валерий Борисович

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