Influence of the structural modulations and the Chain-ladder interaction in the $Sr_{14-x}Ca_{x}Cu_{24}O_{41}$ compounds.

Alain Gellé (1) , Marie-Bernadette Lepetit (1, 2)

1 LPQ - Laboratoire de Physique Quantique
2 CRISMAT - Laboratoire de cristallographie et sciences des matériaux

We studied the effects of the incommensurate structural modulations on the ladder subsystem of the $Sr_{14-x}Ca_{x}Cu_{24}O_{41}$ family of compounds using ab-initio explicitly-correlated calculations. From these calculations we derived $t-J$ model as a function of the fourth crystallographic coordinate $\tau$ describing the incommensurate modulations. It was found that in the highly calcium-doped system, the on-site orbital energies are strongly modulated along the ladder legs. On the contrary the two sites of the ladder rungs are iso-energetic and the holes are thus expected to be delocalized on the rungs. Chain-ladder interactions were also evaluated and found to be very negligible. The ladder superconductivity model for these systems is discussed in the light of the present results.

Mots clés: incommensurate compound; spin chains; spin ladders; ab-initio calculation; electronic structure

Domaines: Electrons fortement corrélés [cond-mat.str-el]

Alain Gellé, Marie-Bernadette Lepetit. Influence of the structural modulations and the Chain-ladder interaction in the $Sr_{14-x}Ca_{x}Cu_{24}O_{41}$ compounds.. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2006, 74, pp.235115. ⟨hal-00003226v4⟩