Volume 86, Number 6, June 2009
Article Number 67007
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 03 July 2009
EPL, 86 (2009) 67007
DOI: 10.1209/0295-5075/86/67007

Experimental evidence of chemical-pressure–controlled superconductivity in cuprates

S. 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 $\leq$ x < 0.5, y $\approx$ 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