Europhys. Lett.
Volume 63, Number 1, July 2003
Page(s) 125 - 131
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 June 2003
DOI: 10.1209/epl/i2003-00487-7
Europhys. Lett., 63 (1) , pp. 125-131 (2003)

Different temperature-dependent local displacements in the underdoped and overdoped $\chem{La}$ 2-x $\chem{Sr}$ x $\chem{CuO_4}$ system

N. L. Saini1, H. Oyanagi2, V. Scagnoli1, T. Ito2, K. Oka2 and A. Bianconi1

1  Unità INFM, Università di Roma "La Sapienza" P. le Aldo Moro 2, 00185 Roma, Italy
2  National Institute for Advanced Industrial Science and Technology 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan

(Received 10 October 2002; accepted in final form 30 April 2003)

$\chem{Cu}$ K-edge extended X-ray absorption fine-structure (EXAFS) measurements have been used to study the temperature-dependent local structure of the underdoped and overdoped superconducting $\chem{La}$ 2-x $\chem{Sr}$ x $\chem{CuO_4}$ system. The Debye-Waller factor of the in-plane $\chem{Cu}$- $\chem{O}$ bonds has been used as an order parameter to measure the local displacements, revealing an anomalous behavior for the underdoped case while the overdoped system shows a negligible change as a function of temperature. The results provide an evidence for a close relationship between local $\chem{Cu}$- $\chem{O}$ displacements, electron-lattice interaction and charge inhomogeneity in the copper oxide superconductors.

74.72.Dn - La-based cuprates.
74.80.-g - Spatially inhomogeneous structures.
61.10.Ht - X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.

© EDP Sciences 2003