Crystal structure and influence of the rare-earth on the magnetic structure of copper germanates R2CuGe4O12
Copper and rare-earth R2CuGe4O12 germanates, R=Y and Eu to Lu, are isostructural, with the symmetry of the triclinic space group P1̄ (No. 2), Z=1. Samples of R=Tb and Dy containing materials have been prepared in polycrystalline form, and their structures have been refined from room temperature high...
| Autores: | , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2002 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/412658 |
| Acceso en línea: | http://hdl.handle.net/10261/412658 https://api.elsevier.com/content/abstract/scopus_id/0037037602 |
| Access Level: | acceso abierto |
| Palabra clave: | Crystal structure and symmetry Magnetically ordered materials Rare-earth germanates |
| Sumario: | Copper and rare-earth R2CuGe4O12 germanates, R=Y and Eu to Lu, are isostructural, with the symmetry of the triclinic space group P1̄ (No. 2), Z=1. Samples of R=Tb and Dy containing materials have been prepared in polycrystalline form, and their structures have been refined from room temperature high-resolution neutron diffraction (ND) data. The structure contains chains of RO7 polyhedra running in the a direction, layers parallel to the ab plane of tetrameric (GeO4)4 units, and isolated CuO6 distorted octahedra which connect these units in the c-direction as well as the RO7 chains along b. Magnetic susceptibility measurements between 1.7 and 350 K reveal for both compounds the existence of one anomaly appearing at T1=6 and 5.5 K, for R=Tb and Dy, respectively. From low temperature ND data, three-dimensional antiferromagnetic (AF) ordering in these compounds is established, with a simultaneous setting up of the order for R3+ and Cu2+ sublattices at TN=T1. Their ordered magnetic structures can be described in terms of a propagation vector k=[1/2, 1/2, 1/2], and accordingly best fits of the 1.6 K experimental ND measurements are favorably explained by a model which consists in the AF arrangement of magnetic moments from both R3+ and Cu2+ magnetic networks along the three axes. Magnetic properties of these compounds are compared with those of other isostructural R2CuGe4O12 germanates. |
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