High-resolution angle-resolved photoemission spectroscopy study of the electronic structure ofEuFe2As2

Abstract

We report the high-resolution angle-resolved photoemission spectroscopy studies of electronic structure of EuFe 2 As 2 . The paramagnetic state data are found to be consistent with density-functional calculations. In the antiferromagnetic ordering state of Fe, our results show that the band splitting, folding, and hybridization evolve with temperature, which cannot be explained by a simple folding picture. Detailed measurements reveal that a tiny electron Fermi pocket and a tiny hole pocket are formed near ͑ , ͒ in the ͑0,0͒ − ͑ , ͒ direction, which qualitatively agree with the results of quantum oscillations, considering k z variation in Fermi surface. Furthermore, no noticeable change within the energy resolution is observed across the antiferromagnetic transition of Eu 2+ ordering, suggesting weak coupling between Eu sublattice and FeAs sublattice.

Quantum oscillations inEuFe2As2single crystals

“…For the parent compounds AFe 2 As 2 (A = Ba, Ca, Eu, Sr, ...), ARPES data usually display four Fe 3d FS sheets in the paramagnetic regime: two electron-like bands around the M -point and two hole-like bands around the Γ-point of the Brillouin zone (BZ). Furthermore, polarized ARPES measurements show the predominance of t 2g orbitals (xy, xz/yz) at the FS with the outer hole-pocket being mostly xy, in agreement with DFT + DMFT calculations 10,12,14,15 . Interestingly, a comparison between Ba122 and Eu122 in the paramagnetic state reveals that the outer hole xy pocket in Ba122 is half the size of Eu122 13 , suggesting an increase of the planar xy occupation in the Ba-rich end.…”

Angle-resolved photoemission study of the role of nesting and orbital orderings in the antiferromagnetic phase of BaFe2As2

“…The details of the droplets and gaps should change along k z , because the sizes of the pockets slightly change. This can actually be observed, 32 but we neglect such effects here, as we have found that they do not modify the general picture.…”

Electronic structure ofBaNi2As2

“…[27][28][29][30][31] The minor lattice distortion cannot account for the large band shift observed in iron pnictides, therefore it has been concluded that the only promising explanation left is that the band shift is related to the magnetism.…”