title: Emergence of a coherent in-gap state in the SmB6 Kondo insulator revealed by scanning tunneling spectroscopy.
abstract: We use scanning tunneling microscopy to investigate the (001) surface of a cleaved SmB6 Kondo insulator. Variable temperature dI/dV spectroscopy up to 60 K reveals a gaplike density of state suppression around the Fermi level, which is due to the hybridization between the itinerant Sm 5d band and localized Sm 4f band. At temperatures below 40 K, a sharp coherence peak emerges within the hybridization gap near the lower gap edge. We propose that the in-gap resonance state is due to a collective excitation in magnetic origin with the presence of spin-orbital coupling and mixed valence fluctuations. These results shed new light on the electronic structure evolution and transport anomaly in SmB6.
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ruan
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China.
authors.forename: Cun
authors.initials: C
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China.
authors.forename: Minghua
authors.initials: M
authors.lastname: Guo
authors.affiliation: Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Chen
authors.affiliation: Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
authors.forename: Xianhui
authors.initials: X
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China.
authors.forename: Guang-Ming
authors.initials: GM
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China and Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China.
authors.forename: Yayu
authors.initials: Y
authors.lastname: Wang