Eur. Phys. J. B 53, 155-167 (2006)
https://doi.org/10.1140/epjb/e2006-00357-8

Effect of structural distortions on the magnetism of doped spin-Peierls CuGeO₃

¹ Laboratoire Louis Néel, B.P. 166, UPR 5051, 38042 Grenoble Cedex 9, France
² CEA-Grenoble, DRFMC / SPSMS / MDN, 38054 Grenoble Cedex 9, France
³ Université Joseph Fourier, B.P. 53, 38041 Grenoble Cedex 9, France
⁴ Laboratoire de Chimie Inorganique et Matériaux Moléculaires, UMR 7071, UPMC, 4 place Jussieu, 75252 Paris Cedex 05, France
⁵ SOLEIL, L'Orme des Merisiers, Saint-Aubin - BP 48, 91192 Gif-sur-Yvette Cedex, France
⁶ Laboratoire de Physico-Chimie de l'État Solide, UMR 8648, Université Paris-Sud, Bât. 414, 91405 Orsay Cedex, France
⁷ Institut d'Électronique Fondamentale, UMR 8622, Bât. 220, Université Paris-Sud, 91405 Orsay Cedex, France

Corresponding author: ^a virginie.simonet@grenoble.cnrs.fr

Received: 4 August 2006
Published online: 27 September 2006

Abstract

The chemical selectivity and great sensitivity of the Extended X-ray Absorption Spectroscopy technique allowed the determination, in the paramagnetic phase, of the structural distortions induced by doping in the spin-Peierls CuGeO₃ compound. The distorted environments were analyzed as a function of concentration, magnetic nature of impurity and the substitution site (Ni, Mn and Zn impurities on the Cu site, Si impurity on the Ge site). This has led to estimate the variation of the angles and pair distances, and hence to evaluate the magnetic coupling along the Cu chains in the vicinity of the impurities. The antiferromagnetic interaction between Cu first neighbors in the pure sample is found to be weakened around Ni, almost cancelled in the case of Mn doping, and even to change sign, producing a ferromagnetic coupling for Si doping. More generally, the structural distortions on a local scale are shown to be key parameters for the understanding of the magnetic properties of doped spin-Peierls compounds.