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Title: Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators

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.

Authors:
; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Excitonics (CE); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Harvard Univ., Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1566683
DOE Contract Number:  
SC0001088; SC0001819
Resource Type:
Journal Article
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 98; Journal Issue: 21; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
solar (photovoltaic), solid state lighting, photosynthesis (natural and artificial), charge transport, optics, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing)

Citation Formats

Nandi, D., Skinner, B., Lee, G. H., Huang, K. -F., Shain, K., Chang, Cui-Zu, Ou, Y., Lee, S. -P., Ward, J., Moodera, J. S., Kim, P., Halperin, B. I., and Yacoby, A. Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators. United States: N. p., 2018. Web. doi:10.1103/physrevb.98.214203.
Nandi, D., Skinner, B., Lee, G. H., Huang, K. -F., Shain, K., Chang, Cui-Zu, Ou, Y., Lee, S. -P., Ward, J., Moodera, J. S., Kim, P., Halperin, B. I., & Yacoby, A. Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators. United States. doi:10.1103/physrevb.98.214203.
Nandi, D., Skinner, B., Lee, G. H., Huang, K. -F., Shain, K., Chang, Cui-Zu, Ou, Y., Lee, S. -P., Ward, J., Moodera, J. S., Kim, P., Halperin, B. I., and Yacoby, A. Sat . "Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators". United States. doi:10.1103/physrevb.98.214203.
@article{osti_1566683,
title = {Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators},
author = {Nandi, D. and Skinner, B. and Lee, G. H. and Huang, K. -F. and Shain, K. and Chang, Cui-Zu and Ou, Y. and Lee, S. -P. and Ward, J. and Moodera, J. S. and Kim, P. and Halperin, B. I. and Yacoby, A.},
abstractNote = {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.},
doi = {10.1103/physrevb.98.214203},
journal = {Physical Review B},
issn = {2469-9950},
number = 21,
volume = 98,
place = {United States},
year = {2018},
month = {12}
}

Works referenced in this record:

Colloquium: Topological insulators
journal, November 2010


Quantum Spin Hall Insulator State in HgTe Quantum Wells
journal, November 2007