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Post KW, Chapler BC, Liu MK, Wu JS, Stinson HT, Goldflam MD, Richardella AR, Lee JS, Reijnders AA, Burch KS, Fogler MM, Samarth N, Basov DN. Sum-rule constraints on the surface state conductance of topological insulators. Phys Rev Lett 2015; 115:116804. [PMID: 26406849 DOI: 10.1103/physrevlett.115.116804] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Indexed: 06/05/2023]
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.
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Affiliation(s)
- K W Post
- Physics Department, University of California-San Diego, La Jolla, California 92093, USA
| | - B C Chapler
- Physics Department, University of California-San Diego, La Jolla, California 92093, USA
| | - M K Liu
- Physics Department, University of California-San Diego, La Jolla, California 92093, USA
| | - J S Wu
- Physics Department, University of California-San Diego, La Jolla, California 92093, USA
| | - H T Stinson
- Physics Department, University of California-San Diego, La Jolla, California 92093, USA
| | - M D Goldflam
- Physics Department, University of California-San Diego, La Jolla, California 92093, USA
| | - A R Richardella
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - J S Lee
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - A A Reijnders
- Department of Physics & Institute for Optical Sciences, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - K S Burch
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - M M Fogler
- Physics Department, University of California-San Diego, La Jolla, California 92093, USA
| | - N Samarth
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - D N Basov
- Physics Department, University of California-San Diego, La Jolla, California 92093, USA
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