Local atomic and electronic structures of the ${\mathrm{YbB}}_{12}$(001) surfaces are studied by scanning tunneling microscopy and spectroscopy at low temperatures for revealing the hybridized surface electronic states. The surface was prepared by annealing in an ultrahigh vacuum at $1200{}^{\circ }\mathrm{C}$ for one hour. The annealing process preferentially removed the surface Yb atoms, and the surface exhibits a homogeneous $c(2\times 2$) structure. On the inhomogeneous surface prepared by $1400{}^{\circ }\mathrm{C}$ annealing for several seconds, there are three types of local $c(2\times 2$) structures. The local tunneling spectra at 5 K near the Fermi energy on the surfaces exhibit characteristic features consisting of a co-tunneling lineshape due to the Kondo lattice formation and an additional central peak. On the homogeneous surface, the shape of the central peak depends on the tip-surface distance, suggesting the $f-d$ hybridized nature of the surface electronic states.

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• Kondo effect
• Surface states
• Topological materials
• Topological phases of matter
• Kondo insulators
• Strongly correlated systems
• Annealing
• Scanning techniques
• Scanning tunneling microscopy
• Scanning tunneling spectroscopy