Evolution of electronic structure in CaFe₂As₂ and EuFe₂As₂ across magnetic transitions

We studied the electronic structure of CaFe2As2 and EuFe2As2 using high resolution photoemission spectroscopy. The Fe 2p and As 3d core‐level spectra of these two compounds show unusual features. The valence band spectra exhibit opening of a gap across SDW transitions. In EuFe2As2, the signature of antiferromagnetic transition is manifested via enhancement of Eu 4f intensity and opening of a second gap at the Fermi level. Interestingly, high resolution spectra of CaFe2As2 also reveal signature of a second gap at lower temperatures although no phase transition was observed in this temperature range