Shifts and Splittings of the Hole Bands in the Nematic Phase of FeSe

We report a high-resolution laser-based angle-resolved photoemission spectroscopy ( laser-ARPES) study of single crystals of FeSe, focusing on the temperature-dependence of the hole-like bands around the Gamma point. As the system cools through the tetragonal-orthorhombic nematic structural transition at 90 K, the splitting of the d(xz)/d(yz) bands is observed to increase by a magnitude of 13 meV. Moreover, the onset of a similar to 10meV downward shift of the d(xy) band is also observed at 90 K. These measurements provide clarity on the nature, magnitude and temperature-dependence of the band shifts at the G point in the nematic phase of FeSe.