2011/12/05 by Hirofumi Sakakibara, H. Sakakibara, H. Usui +7 · 2 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Iron-based superconductors research #Physics of Superconductivity and Magnetism #cond-mat.mtrl-sci #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.85.064501
published as Phys. Rev. B 85, 064501 (2012)
arxiv created 2011/12/05 · openalex publication_date 2012/02/01 · arxiv updated 2012/02/02 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
In order to understand the material dependence of Tc within the single-layered cuprates, we study a two-orbital model that considers both d_x2\ensuremath-y2 and d_z2 orbitals. We reveal that a hybridization of d_z2 on the Fermi surface substantially affects Tc in the cuprates, where the energy difference \ensuremathΔE between the d_x2\ensuremath-y2 and the d_z2 orbitals is identified to be the key parameter that governs both the hybridization and the shape of the Fermi surface. A smaller \ensuremathΔE tends to suppress Tc through a larger hybridization, whose effect supersedes the effect of diamond-shaped (better-nested) Fermi surface. The mechanism of the suppression of d-wave superconductivity due to d_z2 orbital mixture is clarified from the viewpoint of the ingredients involved in the Eliashberg equation, that is, the Green's functions and the form of the pairing interaction described in the orbital representation. The conclusion remains qualitatively the same if we take a three-orbital model that incorporates the Cu 4s orbital explicitly, where the 4s orbital is shown to have an important effect of making the Fermi surface rounded. We have then identified the origin of the material and lattice-structure dependence of \ensuremathΔE, which is shown to be determined by the energy difference \ensuremathΔEd between the two Cu 3d orbitals (primarily governed by the apical oxygen height) and the energy difference \ensuremathΔEp between the in-plane and apical oxygens (primarily governed by the interlayer separation d).