1. Sum-Rule Constraints on the Surface State Conductance of Topological Insulators
- Author
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Nitin Samarth, Joon Sue Lee, Kirk Post, A. Richardella, Jhih-Sheng Wu, B. C. Chapler, H. T. Stinson, Anjan Reijnders, Michael Goldflam, Michael M. Fogler, Mengkun Liu, Kenneth S. Burch, and Dimitri Basov
- Subjects
Physics ,Condensed Matter::Materials Science ,Magnetoresistance ,Condensed matter physics ,Band gap ,Oscillator strength ,Topological insulator ,General Physics and Astronomy ,Charge carrier ,Sum rule in quantum mechanics ,Upper and lower bounds ,Surface states - Abstract
We report the Drude oscillator strength D and the magnitude of the bulk band gap E_{g} of the epitaxially grown, topological insulator (Bi,Sb)_{2}Te_{3}. The magnitude of E_{g}, 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.
- Published
- 2015
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