Orbital-Dependent Modifications of Electronic Structure across the Magnetostructural Transition in BaFe2As2

Laser angle-resolved photoemission spectroscopy (ARPES) is employed to investigate the temperature (T) dependence of the electronic structure in BaFe2As2 across the magnetostructural transition at T-N similar to 140 K. A drastic transformation in Fermi surface (FS) shape across T-N is observed, as expected by first-principles band calculations. Polarization-dependent ARPES and band calculations consistently indicate that the observed FSs at k(z) similar to pi in the low-T antiferromagnetic state are dominated by the Fe3d(zx) orbital, leading to the twofold electronic structure. These results indicate that magnetostructural transition in BaFe2As2 accompanies orbital-dependent modifications in the electronic structure.