title: Electronic structures, hole-doping, and superconductivity of the s = 1, 2, 3, and 4 members of the (Cu,Mo)-12s2 homologous series of superconductive copper oxides.
abstract: We demonstrate that the T(c) value of superconductive copper oxides does not depend on the distance between two adjacent CuO(2) planes as long as the hole-doping level and the immediate (crystal) chemical surroundings of the planes are kept the same. Experimental evidence is accomplished for the homologous series of (Cu,Mo)-12s2, the member phases of which differ from each other by the number (s) of cation layers in the fluorite-structured (Ce,Y)-[O(2)-(Ce,Y)](s-1) block between the CuO(2) planes. X-ray absorption near-edge structure spectroscopy is employed as a probe for the hole states of these phases. The s = 1 member appears to be more strongly doped with holes than other phases of the series and accordingly to possess the highest T(c) value of 87 K. For s > or = 2, unexpectedly, both the CuO(2) plane hole concentration and the value of T(c) (approximately 55 K) remain constant, being independent of s.
authors.affiliation: Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
authors.forename: Inga
authors.initials: I
authors.lastname: Grigoraviciute
authors.forename: Maarit
authors.initials: M
authors.lastname: Karppinen
authors.forename: Ting-Shan
authors.initials: TS
authors.lastname: Chan
authors.forename: Ru-Shi
authors.initials: RS
authors.lastname: Liu
authors.forename: Jin-Ming
authors.initials: JM
authors.lastname: Chen
authors.forename: Omar
authors.initials: O
authors.lastname: Chmaissem
authors.forename: Hisao
authors.initials: H
authors.lastname: Yamauchi