NEUTRON SPECTROSCOPY IN RBA(2)CU(3)O(X) (R=RARE EARTH, 6-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-7) AND R(2-X)CE(X)CUO(4-DELTA) (0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.2) COMPOUNDS - CHARGE-TRANSFER, CLUSTER FORMATION, PERCOLATIVE SUPERCONDUCTIVITY, CHARGE FLUCTUATIONS

被引:18
作者
FURRER, A [1 ]
ALLENSPACH, P [1 ]
FAUTH, F [1 ]
GUILLAUME, M [1 ]
HENGGELER, W [1 ]
MESOT, J [1 ]
ROSENKRANZ, S [1 ]
机构
[1] PAUL SCHERRER INST,CH-5232 VILLIGEN,SWITZERLAND
来源
PHYSICA C | 1994年 / 235卷
关键词
D O I
10.1016/0921-4534(94)91363-3
中图分类号
O59 [应用物理学];
学科分类号
摘要
Neutron spectroscopic experiments performed for the high-T-c superconducting hole-doped RBa(2)Cu(3)Ox (R=rare earth; 6 less than or equal to x less than or equal to 7) and electron-doped R(2-x)Ce(x)CuO(4-delta) (0 less than or equal to x less than or equal to 0.2) compounds are discussed. In these systems the R ions are situated close to the superconducting CuO2 planes, thus the crystal-field interaction at the R site constitutes an ideal local probe of the charge distribution and thereby monitors directly changes of the carrier concentration induced by doping. For several compounds the observed crystal-field spectra separate into different local components whose spectral weights distinctly depend on the doping level, i.e., there is clear experimental evidence for cluster formation. The onset of superconductivity can be shown to result from percolation, i.e., the superconductivity is an inhomogeneous property in the persovskite-type compounds. From a line-width analysis of the observed crystal-field transitions we derive the evolution of the fractal sizes of the clusters versus doping. At high doping the neutron spectroscopic data reveal anomalies which are interpreted in terms of copper-oxyde charge fluctuations.
引用
收藏
页码:261 / 264
页数:4
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