Electronic Band Structure of the Pyrochlore Ruthenium Oxides A 2 Ru 2 O 7 ( A = B i , Tl and Y)
2000; Physical Society of Japan; Volume: 69; Issue: 2 Linguagem: Inglês
10.1143/jpsj.69.526
ISSN1347-4073
Autores Tópico(s)Crystal Structures and Properties
ResumoA local-density electronic-band-structure calculation was performed for pyrochlore ruthenium oxides A 2 Ru 2 O 7 ( A = Bi, Tl and Y). As a general feature, these pyrochlores have band structure composed of antibonding states of Ru 4 d ( t 2 g ) and O 2 p orbitals near the Fermi energy ( E F ) analogous to the layered perovskite superconductor Sr 2 RuO 4 . It was found that effects of A ion's orbitals to the band structure near E F are quite important in the pyrochlores. Specifically in Tl 2 Ru 2 O 7 , bands which consist of antibonding states of Tl 6 s and O 2 p orbitals exist with nearly half-fillings. A tight-binding model shows an energy-gap formation of the Tl-O bands with an orthorhombic lattice distortion. The calculated result suggests importance of coupling between electronic and lattice instabilities, which may be a clue to understand metal-insulator transition observed in Tl 2 Ru 2 O 7 .
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