Dirac-like band dispersion at the pyrite-type <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>CuSe</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:math> (100) surface revealed by soft x-ray angle-resolved photoemission spec

We have investigated the bulk and surface electronic structure of pyrite-type ${\mathrm{CuSe}}_{2}$ by means of soft x-ray photoemission spectroscopy. The Cu $3d$ band around 2.5 eV below the Fermi level does not show Cu $2p\text{\ensuremath{-}}3d$ resonance indicating that the Cu $3d$ level is almost fully filled and the Cu valence is close to $+1$. The dispersions of the Cu $3d/\mathrm{Se}\phantom{\rule{0.28em}{0ex}}4p$ bands observed by angle-resolved measurements roughly follow slab calculations for (100) surface. The surface of pyrite-type ${\mathrm{CuSe}}_{2}$ harbors two-dimensional Dirac-like band dispersions at the corner of the surface Brillouin zone suggesting possible interplay between the surface/interface Dirac states and the exotic bulk electronic/lattice properties through the Cu $3d$-Se $4p$ interaction.