Scanning Tunneling Microscopy Studies of the Topological Insulator Candidate YbB$_6$*

We report scanning tunneling microscopy studies of YbB$_6$, a proposed topological insulator candidate with moderate correlation. The in-situ cleaved sample surface has two dominant morphologies: atomic square lattices and disordered rows, which likely correspond to Yb and B terminations, respectively. Spatially resolved $dI/dV$ maps show enhanced tunneling due to the local perturbation of the tip-induced band bending. The $dI/dV$ spectra reveal a bulk gap with distinct in-gap features near the Fermi level on different terminations. Our study presents nanoscale evidence for the interplay between surface structure, correlation and topological properties.