Observation of Fermi-energy dependent unitary impurity resonances in a strong topological insulator Bi_2Se_3 with scanning tunneling spectroscopy

Creators: Teague, M. L.; Chu, H.; Xiu, F.-X.; He, L.; Wang, K.-L.; Yeh, N.-C.

Abstract

Scanning tunneling spectroscopic studies of Bi_2Se_3 epitaxial films on Si (111) substrates reveal highly localized unitary impurity resonances associated with non-magnetic quantum impurities. The strength of the resonances depends on the energy difference between the Fermi level (E_F) and the Dirac point (E_D) and diverges as E_F approaches E_D. The Dirac-cone surface state of the host recovers within ~ 2Å spatial distance from impurities, suggesting robust topological protection of the surface state of topological insulators against high-density impurities that preserve time reversal symmetry.

Additional Information

© 2012 Elsevier Ltd. Received 16 January 2012. Accepted 26 January 2012 by A. Pinczuk. Available online 1 February 2012. This work at Caltech was jointly supported by the Center on Functional Engineered Nano Architectonics (FENA), the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center with support of the Gordon and Betty Moore Foundation, and the Kavli Foundation through the Kavli Nanoscience Institute (KNI) at Caltech. The work at UCLA was supported by FENA. We thank K. Sengupta and A. V. Balatsky for valuable discussion.

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