Synthesis, structural and magnetic disordering in the IrSr₂RECu₂O_8+x family of metalo-cuprates by HP+HT oxidation

Abstract

In this work, we report the preparation of both ordered and disordered phases in the IrSr₂RECu₂O₈ family by high pressure and high temperature oxidation. This chemical oxidation process is accompanied by a disordering of the metal sublattices of the triple perovskite cell (i.e. IrSr₂RECu₂O₈) to an AA′ and BB′ disordered simple perovskite (Sr₂RE)(Cu₂Ir)O_9−δ. It is especially relevant that both phases have exactly the same cation stoichiometry but different oxygen content. The disordering induced in the cation sublattices has dramatic consequences in the magnetic properties of these compounds.

Keywords:

• 1212-cuprates
• irido-cuprates
• order–disorder oxidation
• high pressure
• perovskite

Acknowledgements

We thank Dr J.M. Gallardo Amores and Dr J. Romero for help with the sample preparation and susceptibility measurements. The authors are also indebted to Dr H. Huppertz and Dr G. Heymann in the synthesis of some samples. Some other HP experiments were performed at the Bayerisches Geoinstitut under the EU “Research Infrastructures: Transnational Access Programme (Contract No. 505320 (RITA)-High Pressure)” program. Financial support was provided by CICYT through projects MAT2004-01641 and MAT2007-64006, Comunidad Autónoma de Madrid through MATERYENER program PRICYT S-0505/PPQ-0093 (2006) and CONACYT México. We also thank Prof. David Rubie for valuable comments.