Presentation Information
[2I03]Hybridization gap and in-gap surface electronic states of atomically ordered YbB12(001) surfaces
*Fumio Komori1,2,3, Kota Iwata1, Takushi Iimori1, Shunsuke Yoshizawa4, Yoshiyuki Ohtsubo5,6, Takuto Nakamura6, Shin-ichi Kimura5,6, Fumitoshi Iga7,8, Toshio Miyamachi1,2 (1. Institute for Solid State Physics, University of Tokyo, 2. Institute of Materials and Systems for Sustainability, Nagoya University, 3. School of Materials and Chemical Technology, Institute of Science Tokyo, 4. Center for Basic Research on Materials, National Institute for Materials Science (NIMS), 5. Graduate School of Frontier Biosciences, Osaka University, 6. Graduate School of Science, Osaka University, 7. College of Science, Ibaraki University, 8. Institute of Quantum Beam Science, Ibaraki University)
We have studied the surface structure and electronic states using STM/STS on the (001) surface of an YbB12 crystal. By annealing it at 1200 oC for one hour, we successfully prepared a flat and well-ordered YbB12(001)-c(2x2) surface, Surface#1. The surface prepared by flash annealing at 1400 oC, Surface#2, also show flat surface, but the local structure is inhomogeneous; there are typical three kinds of local c(2x2) structures. The observed local tunneling spectra on the surfaces are commonly decomposed by a broad co-tunneling lineshape and a peak near Fermi energy while their shape depends on the local atomic structure. The peak consists of two Gaussian components on Surface#1 with the common peak positions in the tip-surface dependent spectra. These are attributed to the lower edge of the 4f-5d hybridization gap and an in-gap topological surface state.