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Electronic structure and coexistence of superconductivity with magnetism in RbEuFe4As4
In the novel stoichiometric iron-based material RbEuFe4As4, superconductivity coexists with a peculiar longrange
magnetic order of Eu 4f states. Using angle-resolved photoemission spectroscopy, we reveal a complex
three-dimensional electronic structure and compare it with density functional theory calculations.Multiple superconducting
gaps were measured on various sheets of the Fermi surface. High-resolution resonant photoemission
spectroscopy reveals magnetic order of the Eu 4f states deep into the superconducting phase. Both the absolute
values and the anisotropy of the superconducting gaps are remarkably similar to the sibling compound without
Eu, indicating that Eu magnetism does not affect the pairing of electrons. A complete decoupling between Feand
Eu-derived states was established from their evolution with temperature, thus unambiguously demonstrating
that superconducting and a long-range magnetic orders exist independently from each other. The established
electronic structure of RbEuFe4As4 opens opportunities for the future studies of the highly unorthodox electron
pairing and phase competition in this family of iron-based superconductors with doping