SUPERCONDUCTIVITY IN TLSR2-XCAXYBCU2O7 BY ISOVALENT CATION SUBSTITUTION

Authors
OHSHIMA E KIKUCHI M SYONO Y
Citation
E. Ohshima et al., SUPERCONDUCTIVITY IN TLSR2-XCAXYBCU2O7 BY ISOVALENT CATION SUBSTITUTION, Physica. C, Superconductivity, 269(3-4), 1996, pp. 225-230
Citations number
22
Categorie Soggetti
Physics, Applied
Journal title
Physica. C, Superconductivity → ACNP
ISSN journal
09214534
Volume
269
Issue
3-4
Year of publication
1996
Pages
225 - 230
Database
ISI
SICI code
0921-4534(1996)269:3-4<225:SITBIC>2.0.ZU;2-O
Abstract
TlSr2YbCu2O7 was found to be non-superconducting, in harmony with the formal valence of Cu2+ and Tl3+. However, isovalent cation substitutio n of Ca2+ for Sr2+ made TlSr2-xCaxYbCu2O7 superconducting for x greate r than or equal to 0.2, although no change would be expected in the fo rmal valence of Cu. These observations strongly suggest that hole carr iers are self-doped due to overlap between Tl6s and Cu3d(x2-y2) bands, which is enhanced by the observed shortening of the Cu-O bond length in the CuO2 sheet by Ca substitution for Sr.