and the top of the [$d_{xz}$/$d_{yz}$]{} hole band be degenerate. Since the shallow electron band is separated from the hole band by more than 70meV, it is unlikely to be the [$d_{xz}$/$d_{yz}$]{} electron band, but is instead the [$d_{xy}$]{} band.

There is in principle the possibility of an alternative understanding. As described in Ref. [@s4Lin; @s4Brouet], the alternating arsenic atoms about the iron plane may induce parity-switching of certain orbitals when folding from the 1-Fe BZ to the 2-Fe BZ, which would swap the orbital characters of the [$d_{xz}$]{} electron band and the [$d_{xy}$]{} electron band at X along $\Gamma$-X direction, making the originally [$d_{xz}$]{} electron band to be more observable under an odd polarization (Fig. \[fig:fig1\]c). Under this understanding, the shallow band is still the [$d_{xz}$]{} band rather than the [$d_{xy}$]{} band. However, for this understanding to hold, the aforementioned degeneracy of the [$d_{xz}$/$d_{yz}$]{} bands must be lifted to account for the 70meV gap between the shallow electron band and the hole band at X.

There are two mechanisms that could lift this degeneracy. One is spin-orbit coupling. However, in this compound, the magnitude of the spin-orbit coupling is not strong enough to cause such a large gap. Moreover, 