Novel magnetic stoichiometric superconductor compound EuRbFe4As4

In the new stoichiometric high-temperature ironbased superconductor RbEuFe4As4, superconductivity coexists with a peculiar long-range magnetic order of the Eu 4f states; their coexistence is an enigma and a challenge for both experiment and theory. Using angle-resolved photoemission spectroscopy (ARPES), resonant photoemission spectroscopy (ResPES), Andreev reflection spectroscopy, scanning tunneling spectroscopy, and DFT band structure calculations, we have made significant progress in solving this puzzle. Our results unambiguously indicate a separation between the electronic states of Fe (superconductivity) and Eu (magnetism) and demonstrate the existence of superconducting and long-range magnetic orders almost independently of each other.