Sum-Rule Constraints on the Surface State Conductance of Topological Insulators

K. W. Post, B. C. Chapler, M. K. Liu, J. S. Wu, H. T. Stinson, M. D. Goldflam, A. R. Richardella, J. S. Lee, A. A. Reijnders, K. S. Burch, M. M. Fogler, N. Samarth, D. N. Basov

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


We report the Drude oscillator strength D and the magnitude of the bulk band gap Eg of the epitaxially grown, topological insulator (Bi,Sb)2Te3. The magnitude of Eg, in conjunction with the model independent f-sum rule, allows us to establish an upper bound for the magnitude of D expected in a typical Dirac-like system composed of linear bands. The experimentally observed D is found to be at or below this theoretical upper bound, demonstrating the effectiveness of alloying in eliminating bulk charge carriers. Moreover, direct comparison of the measured D to magnetoresistance measurements of the same sample supports assignment of the observed low-energy conduction to topological surface states.

Original languageEnglish (US)
Article number116804
JournalPhysical review letters
Issue number11
StatePublished - Sep 11 2015

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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