Reproduction of Experimental Gap Structure in LiFeAs based on the Orbital-Spin Fluctuation Theory: $s_{++}$-wave, $s_{\pm }$-wave, and hole-$s_{\pm }$-wave states

Abstract

The absence of nesting between electron and hole-pockets in LiFeAs with $T_c=18$K attracts great attention, as an important hint to understand the pairing mechanism of Fe-based superconductors. Here, we study the five-orbital model of LiFeAs based on the recently-developed orbital-spin fluctuation theories. It is found that the experimentally observed gap structure of LiFeAs, which is a "fingerprint" of the pairing mechanism, is quantitatively reproduced in terms of the orbital-fluctuation-mediated $s_{++}$-wave state. Especially, the largest gap observed on the small two hole-pockets composed of ($d_{xz},d_{yz}$) orbitals can be explained, and this is a hallmark of the orbital-fluctuation-mediated superconductivity. The $s_{++}$-wave gap structure becomes more anisotropic in the presence of weak spin fluctuations. As the spin fluctuations increase, we obtain the "hole-$s_{\pm }$-wave state", in which only the gap of the large hole-pocket made of $d_{xy}$-orbital is sign-reversed, due to the cooperation of orbital and spin fluctuations. %out of the five pockets. This gap structure with "sign-reversal between hole-pockets" is similar to that recently reported in (Ba,K)Fe${}_2$As${}_2$.

11 pages, 10 figures, figures and explanations have been revised, to be published in Phys. Rev. B

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Cited by in corpus (8)

• Iron-Based Superconductors: current status of materials and pairing mechanism
• Observation of strong electron pairing on bands without Fermi surfaces in LiFe1-xCoxAs
• ARPES measurements of the superconducting gap of Fe-based superconductors and their implications to the pairing mechanism
• Vortex phase diagram and the normal state of cuprates with charge and spin orders
• The spectral weight of hole doped cuprates across the pseudogap critical point
• The Three-Dimensional Electronic Structure of LiFeAs: Strong-coupling Superconductivity and Topology in the Iron Pnictides
• Collective Dynamics and Strong Pinning near the Onset of Charge Order in La${}_{1.48}$Nd${}_{0.4}$Sr${}_{0.12}$CuO${}_4$
• Light-Induced Melting of Competing Stripe Orders without Introducing Superconductivity in La${}_{2-\mathbf{x}}$Ba${}_{\mathbf{x}}$CuO${}_4$