Evolution of electronic structure in CaFe₂As₂ and EuFe₂As₂ across magnetic transitions

Abstract

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.