Metal-nonmetal changeover in pyrochlore iridates

We report the low temperature properties of a new series of pyrochlore iridates R2Ir2O7 (R=rare-earth elements). We found that the compounds with R=Pr, Nd, Sm, and Eu exhibit metallic conductivity, whereas those with smaller rare-earth ions are nonmetallic. Such metal-nonmetal changeover is attribut...

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Bibliographic Details
Published in:Journal of the Physical Society of Japan 2001-10, Vol.70 (10), p.2880-2883
Main Authors: YANAGISHIMA, Daiki, MAENO, Yoshiteru
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electronic transport in condensed matter
Exact sciences and technology
Exchange and superexchange interactions
Magnetic properties and materials
Magnetically ordered materials: other intrinsic properties
Mixed conductivity and conductivity transitions
Physics
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Summary:We report the low temperature properties of a new series of pyrochlore iridates R2Ir2O7 (R=rare-earth elements). We found that the compounds with R=Pr, Nd, Sm, and Eu exhibit metallic conductivity, whereas those with smaller rare-earth ions are nonmetallic. Such metal-nonmetal changeover is attributable to the importance of electron correlation among the Ir 5d electrons. Reflecting the geometrical frustration in the pyrochlore lattice, the rare-earth moments do not exhibit magnetic ordering to temperatures well below the antiferromagnetic Weiss temperature. We did not find any sign of superconductivity down to 0.3 K in these compounds.
ISSN:0031-9015
1347-4073
DOI:10.1143/jpsj.70.2880