Vijayaraghavan, R and Ganguli, AK and Vasanthacharya, NY and Rajumon, MK and Kulkarni, GU and Sankar, G and Sarma, DD and Sood, AK and Chandrabhas, N and Rao, CNR (1989) Investigation of novel cuprates of the TlCa1-xLnxSr2Cu2O7- δ (Ln=rare earth) series showing electron- or hole-superconductivity depending on the composition. In: Superconductor Science and Technology, 2 (3). pp. 195-201.
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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.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Institute of Physics.|
|Department/Centre:||Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Division of Physical & Mathematical Sciences > Physics
|Date Deposited:||05 Aug 2010 10:58|
|Last Modified:||19 Sep 2010 06:13|
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