2012/02/29 by Jiangping Hu, Ningning Hao · 1 citation
Physics and Astronomy · #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevx.2.021009
published as Phys. Rev. X 2, 021009 (2012) · 8 figures. 10 pages. Note: the paper Arxiv:1203.2304 are combined together in this new version
arxiv created 2012/06/04 · arxiv updated 2012/06/05
Although iron-based superconductors are multi-orbital systems with complicated band structures, we demonstrate that the low energy physics which is responsible for high-Tc superconductivity is essentially governed by one effective Hamiltonianwith two almost decoupled orbitals near half filling. This underlining electronic structure is protected by the S4 symmetry. With repulsive or strong next nearest neighbor antiferromagnetic exchange interactions, each single-orbital effective Hamiltonian results in a robust A1g s-wave pairing which can be exactly mapped to the d-wave pairing observed in cuprates. The classification of the superconducting(SC) states according to the S4 symmetry leads to a natural prediction of the existence of two different phases named A and B phases. In the B phase, the superconducting order has an overall sign change along c-axis between the top and bottom As(Se) planes in a single Fe-(As)Se trilayer structure, which is an analogy of the sign change under the 90^∘ degree rotation in the d-wave SC state of cuprates. Our derivation provides a unified understanding of iron-pnictides and iron-chalcogenides, and suggests that cuprates and iron-based superconductors share identical high-Tc superconducting mechanism.