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Title: Investigation of novel cuprates of the TlCa1-xLnxSr2Cu2O7- δ (Ln=rare earth) series showing electron- or hole-superconductivity depending on the composition
Authors: Vijayaraghavan, R
Ganguli, A K
Vasanthacharya, N Y
Rajumon, M K
Kulkarni, G U
Sankar, G
Sarma, D D
Sood, A K
Narayana, Chandrabhas
Rao, C N R
Keywords: Superconductivity in cuprates
TlCa1-xLnxSr2Cu2O7+ delta
Ln=rare earth
electron- or hole-superconductivity
metal-insulator transitions
Raman frequency
Issue Date: 1989
Publisher: IOP Publishing Ltd
Citation: Superconductor Science and Technology 2(3), 195-201 (1989)
Abstract: Superconductivity in cuprates of the general formula TlCa1-xLnxSr2Cu2O7+ delta has been investigated as a function of Ln and x. Compositions with 0.25<or=x<or=0.8 are superconducting for all Ln with Tc in the range 60-90 K (except when Ln=Yb where x=1 is also superconducting); the value of the Tc varies with x as well as Ln. When x approximately=0.25, electrons are the majority charge carriers, while holes are the majority carrier when x >0.25. Thus, these cuprates exhibit a composition-dependent electron- or hole-superconductivity. In the normal state, most of the members of the series traverse compositionally determined metal-insulator transitions. High-energy spectroscopies show the presence of Cu in the 1+ and 2+ states. The Raman frequency around 525 cm-1 characteristic of the Tl-O2-Cu linkage is sensitive to both Ln and x, indicating a possible involvement in the mechanism of superconductivity.
Description: Restricted Access
Other Identifiers: 0953-2048
Appears in Collections:Research Papers (Prof. C.N.R. Rao)

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