Investigation of novel cuprates of the TlCa1-xLnxSr2Cu2O7- δ(Ln=rare earth) series showing electron- or hole-superconductivity depending on the composition

Abstract
Superconductivity in cuprates of the general formula TlCa1-xLnxSr2Cu2O7+ delta has been investigated as a function of Ln and x. Compositions with 0.25-1 characteristic of the Tl-O2-Cu linkage is sensitive to both Ln and x, indicating a possible involvement in the mechanism of superconductivity.