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arXiv · 1304.5043

Material Optimization for Fermi Surface Shape Control of Tl-based Cuprate Superconductors

Satoaki Miyao·Hirofumi Sakakibara·Isao Maruyama·Kazuhiko Kuroki·Koichi Kusakabe
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Abstract

To show an optimization method of element substitution for cuprate superconductors, we investigate Fermi surface shape of TlR2A2Cu3O9 with R=La, Y, and A=Li, Na, K, Rb, Cs. We adopt the generalized gradient approximation in the density-functional theory (DFT-GGA) for the study of over-doped phases of these unknown cuprates. The electronic structures of crystals optimized by DFT-GGA show systematic element dependence in a Fermi surface shape controlling parameter, r, of Cu dx2-y2 bands, where nearly absent dz2 component at the Fermi level and smaller r keeping t1 suggest enhancement of the superconducting transition temperature within the spin-fluctuation mechanism. For TlYRb2Cu3O9, smaller r by a reduction factor larger than 10% compared to a reference system of TlBa2Ca2Cu3O9 (TBCCO) appears in the outer CuO2 plane, but with 12 % reduction in t1. For TlR2Li2Cu3O9, (R=Y, La), smaller r by a factor larger than 1% appears keeping t1 as large as TBCCO in the inner plane. Our method may be used to predict an optimized material structure referencing known cuprate superconductors.

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Satoaki Miyao, Hirofumi Sakakibara, Isao Maruyama, Kazuhiko Kuroki, Koichi Kusakabe. 2013-04-24. Material Optimization for Fermi Surface Shape Control of Tl-based Cuprate Superconductors. https://arxiv.org/abs/1304.5043

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