Electronic Structure of Yb(Ni1-xCox)(3)Ga-9 Studied by Angle-resolved Photoelectron Spectroscopy

Chiral crystal YbNi3Ga9 is known as an intermediate valence compound in which a strong hybridization between the 4f orbitals and the conduction band is present. The Co-substitution to YbNi3Ga9 works as a hole doping that reduces the Kondo temperature and enhances the effective mass of itinerant charge carriers. Using angle-resolved photoelectron spectroscopy, the complex band structure of Yb(Ni1-xCox)(3)Ga-9 (x = 0, 0.1) is revealed. A Yb2+ 4f(7/2) band and evidences of hybridization to valence bands are found near the Fermi level. Both YbNi3Ga9 and the Co-substituted compound exhibit double hexagonal Fermi surfaces centered at the (Gamma) over bar -point, surrounded by a large snowflake-like surface, and a triangular electron-like surface along the (Gamma) over bar(M) over bar direction. By changing the incident photon energy, the band dispersion along the c-axis and the barrel-shaped Fermi surface is observed.