Fate of $yz$/$zx$ orbital degeneracy and $xy$ Fermi surface in Ru substituted FeSe${}_{1-x}$Te${}_x$

Abstract

We have investigated the impact of Ru substitution on the multi-band electronic structure of FeSe${}_{1-x}$Te${}_x$ by means of angle-resolved photoemission spectroscopy (ARPES). The ARPES results exhibit suppression of the $xy$ Fermi surface and the spectral broadening near the zone boundaries, which can be associated with the lattice disorder introduced by the Ru substitution. The degeneracy of the Fe 3$d$ $yz$/$zx$ bands at the zone center, which is broken in FeSe${}_{1-x}$Te${}_x$, is partly recovered with the Ru substitution, indicating coexistence of nematic and non-nematic electronic states.

5 pages, 4 figures