Experimental evidence of chemical-pressure–controlled superconductivity in cupratesS. Sanna1, 2, S. Agrestini3, K. Zheng2, R. De Renzi2 and N. L. Saini4
1 Dipartimento di Fisica and CNISM, Università di Pavia - viale Bassi 6, 27100 Pavia, Italy, EU
2 Dipartimento di Fisica and CNISM, Università di Parma - viale Usberti 7A, 43100 Parma, Italy, EU
3 Laboratoire CRISMAT, UMR 6508, ENSICAEN-CNRS - Boulevard du Marechal Juin, 14050 Caen, France, EU
4 Dipartimento di Fisica, Università di Roma “La Sapienza” - P.le Aldo Moro 2, 00185 Roma, Italy, EU
received 27 April 2009; accepted in final form 2 June 2009; published June 2009
published online 3 July 2009
X-ray absorption spectroscopy (XAS) and high-resolution X-ray diffraction are combined to study the interplay between electronic and lattice structures in controlling the superconductivity in cuprates with a model charge-compensated CaxLa1- xBa1.75-xLa0.25+xCu3Oy (0 x < 0.5, y 7.13) system. In spite of a large change in Tc, the doped holes, determined by the Cu L and O K XAS, hardly show any variation with the x. On the other hand, the CuO2 plaquette size shows a systematic change due to different size of substituted cations. The results provide a direct evidence for the chemical pressure being a key parameter for controlling the superconducting ground state of the cuprates.
74.72.-h - Cuprate superconductors (high-Tc and insulating parent compounds).
74.62.Dh - Effects of crystal defects, doping and substitution.
78.70.Dm - X-ray absorption spectra.
© EPLA 2009