| Summary: | A Kene–Mele-type nearest-neighbor tight-binding model on a pyrochlore lattice is known to be a topological insulator in some parameter region. It is an important task to realize a topological insulator in a real compound, especially in an oxide that is stable in air. In this paper we systematically performed band structure calculations for six pyrochlore oxides A<sub>2</sub>B<sub>2</sub>O<sub>7</sub> (A = Sn, Pb, Tl; B = Nb, Ta), which are properly described by this model, and found that heavily hole-doped Sn<sub>2</sub>Nb<sub>2</sub>O<sub>7</sub> is a good candidate. Surprisingly, an effective spin–orbit coupling constant λ changes its sign depending on the composition of the material. Furthermore, we calculated the band structure of three virtual pyrochlore oxides, namely In<sub>2</sub>Nb<sub>2</sub>O<sub>7</sub>, In<sub>2</sub>Ta<sub>2</sub>O<sub>7</sub> and Sn<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub>. We found that Sn<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> has a band gap at the <b><i>k</i></b> = 0 (Γ) point, similar to Sn<sub>2</sub>Nb<sub>2</sub>O<sub>7</sub>, though the band structure of Sn<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> itself differs from the ideal nearest-neighbor tight-binding model. We propose that the co-doped system (In,Sn)<sub>2</sub>(Nb,Zr)<sub>2</sub>O<sub>7</sub> may become a candidate of the three-dimensional strong topological insulator.
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