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Bulk metals with helical surface states

Bergman, Doron L. and Refael, Gil (2010) Bulk metals with helical surface states. Physical Review B, 82 (19). Art. No. 195417 . ISSN 0163-1829. doi:10.1103/PhysRevB.82.195417.

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In the flurry of experiments looking for topological insulator materials, it has been recently discovered that some bulk metals very close to topological insulator electronic states support the same topological surface states that are the defining characteristic of the topological insulator. First observed in spin-polarized angle resolved photoemission spectroscopy (ARPES) in Sb [D. Hsieh et al., Science 323, 919 (2009)], the helical surface states in the metallic systems appear to be robust to at least mild disorder. We present here a theoretical investigation of the nature of these “helical metals”—bulk metals with helical surface states. We explore how the surface and bulk states can mix, in both clean and disordered systems. Using the Fano model, we discover that in a clean system, the helical surface states are not simply absorbed by hybridization with a nontopological parasitic metallic band. Instead, they are pushed away from overlapping in momentum and energy with the bulk states, leaving behind a finite-lifetime surface resonance in the bulk energy band. Furthermore, the hybridization may lead in some cases to multiplied surface-state bands, in all cases retaining the helical characteristic. Weak disorder leads to very similar effects—surface states are pushed away from the energy bandwidth of the bulk, leaving behind a finite-lifetime surface resonance in place of the original surface states.

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Additional Information:© 2010 The American Physical Society. Received 21 May 2010; revised manuscript received 13 October 2010; published 9 November 2010. It is a pleasure to acknowledge useful discussions with P. A. Lee, O. Motrunich, Z. Hasan, and D. Hsieh. D.L.B. is grateful for support by the Sherman Fairchild Foundation. G.R. is grateful for the generous support of the Packard Foundation, the Sloan Foundation, and the FENA Focus Center, one of six research centers funded under the Focus Center Research Program (FCRP), a Semiconductor Research Corporation entity.
Funding AgencyGrant Number
Sherman Fairchild FoundationUNSPECIFIED
Focus Center Research Program (FCRP)UNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Issue or Number:19
Classification Code:PACS: 73.20.At
Record Number:CaltechAUTHORS:20101215-110525362
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21376
Deposited By: Tony Diaz
Deposited On:15 Dec 2010 19:46
Last Modified:09 Nov 2021 00:08

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