Two-Orbital Model Explains the Higher Transition Temperature of the Single-Layer Hg-Cuprate Superconductor Compared to That of the La-Cuprate Superconductor

2010/03/31 by Hirofumi Sakakibara, Hidetomo Usui, Kazuhiko Kuroki +2 · 1 citation
Physics and Astronomy · #cond-mat.supr-con

paper · pdf · doi:10.1103/physrevlett.105.057003

published as Phys. Rev. Lett. 105, 057003 (2010) · 4 pages, 4 figures. Final version published in Phys. Rev. Lett

arxiv created 2010/08/03 · arxiv updated 2010/08/04

Abstract

In order to explore the reason why the single-layered cuprates, La_2-x(Sr/Ba)_xCuO₄ (T_c≃ 40K) and HgBa₂CuO_4+δ (T_c≃ 90K), have such a significant difference in T_c, we study a two-orbital model that incorporates the d_z² orbital on top of the d_x²-y² orbital. It is found, with the fluctuation exchange approximation, that the d_z² orbital contribution to the Fermi surface, which is stronger in the La system, works against d-wave superconductivity, thereby dominating over the effect of the Fermi surface shape. The result resolves the long-standing contradiction between the theoretical results on Hubbard-type models and the experimental material dependence of T_c in the cuprates.

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