Lifting of<i>xz</i>/<i>yz</i>orbital degeneracy at the structural transition in detwinned FeSe
Lifting of<i>xz</i>/<i>yz</i>orbital degeneracy at the structural transition in detwinned FeSe
We study superconducting FeSe $({T}_{\mathrm{c}}\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}9\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ exhibiting the tetragonal-orthorhombic structural transition $({T}_{\mathrm{s}}\phantom{\rule{0.16em}{0ex}}\ensuremath{\sim}\phantom{\rule{0.16em}{0ex}}90\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ without any antiferromagnetic ordering, by utilizing angle-resolved photoemission spectroscopy. In the detwinned orthorhombic state, the energy position of the ${d}_{yz}$ orbital band at the Brillouin zone corner is $50\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$ higher than that of ${d}_{xz}$, indicating the orbital order similar …