Fate of $yz$/$zx$ orbital degeneracy and $xy$ Fermi surface in Ru   substituted FeSe$_{1-x}$Te$_{x}$
  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. 
T. Sugimoto, D. Ootsuki, K. Sawada, H. Anzai, M. Arita, H. Namatame,   M. Taniguchi, M. Horio, K. Horiba, M. Kobayashi, K. O...
cond-mat.supr-con