Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators
Name
PhysRevB.98.214203.pdf
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3.17 MB
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Checksum (MD5)
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Author(s)
Lee, G. H.
Huang, K.-F.
Shain, K.
Lee, S.-P.
Ward, J.
Kim, P.
Halperin, B. I.
Yacoby, A.
Nandi, Debaleena
Skinner, Barbara
Date Issued
December 2018
Journal
Physical Review B
Publisher
American Physical Society
Citation
Nandi, D. et al. "Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators." Physical Review B 98, 21 (December 2018): 214203 © 2018 American Physical Society
Version
Final published version
Abstract
In an ultrathin topological insulator (TI) film, a hybridization gap opens in the TI surface states, and the system is expected to become either a trivial insulator or a quantum spin Hall insulator when the chemical potential is within the hybridization gap. Here we show, however, that these insulating states are destroyed by the presence of a large and long-range-correlated disorder potential, which converts the expected insulator into a metal. We perform transport measurements in ultrathin dual-gated topological insulator films as a function of temperature, gate voltage, and magnetic field, and we observe a metalliclike nonquantized conductivity, which exhibits a weak antilocalizationlike cusp at low magnetic fields and gives way to a nonsaturating linear magnetoresistance at large fields. We explain these results by considering the disordered network of electron- and hole-type puddles induced by charged impurities. We argue theoretically that such disorder can produce an insulator-to-metal transition as a function of increasing disorder strength, and we derive a condition on the band gap and the impurity concentration necessary to observe the insulating state. We also explain the linear magnetoresistance in terms of strong spatial fluctuations of the local conductivity using both numerical simulations and a theoretical scaling argument.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Plasma Science and Fusion Center
Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology)
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.98.214203
