Conductance Spectroscopy of Exfoliated Thin Flakes of NbxBi2Se3

Kurter, C.; Finck, A. D.  K.; Huemiller, E. D.; Medvedeva, J.; Weis, A.; Atkinson, J. M.; Qiu, Y.; Shen, L.; Lee, S. H.; Vojta, T.; Ghaemi, P.; Hor, Y. S.; Van Harlingen, D. J.

doi:10.1021/acs.nanolett.8b02954

Title: Conductance Spectroscopy of Exfoliated Thin Flakes of Nb_xBi₂Se₃

Journal Article · Tue Nov 27 00:00:00 EST 2018 · Nano Letters

DOI:https://doi.org/10.1021/acs.nanolett.8b02954· OSTI ID:1543686

^[1]; Finck, A. D. K. ^[2]; Huemiller, E. D. ^[3]; Medvedeva, J. ^[4]; Weis, A. ^[3]; Atkinson, J. M. ^[3]; Qiu, Y. ^[4]; Shen, L. ^[4]; Lee, S. H. ^[4]; Vojta, T. ^[4]; Ghaemi, P. ^[5]; Hor, Y. S. ^[4]; Van Harlingen, D. J. ^[3]

Missouri Univ. of Science and Technology, Rolla, MO (United States); Univ. of Illinois at Urbana-Champaign, IL (United States)
Univ. of Illinois at Urbana-Champaign, IL (United States); IBM Thomas J. Watson Research Center, Yorktown Heights, NY (United States)
Univ. of Illinois at Urbana-Champaign, IL (United States)
Missouri Univ. of Science and Technology, Rolla, MO (United States)
City College of New of CUNY, New York, NY (United States); Department of Physics, Graduate Center of CUNY, New York, NY (United States)

We study unconventional superconductivity in exfoliated single crystals of a promising three-dimensional (3D) topological superconductor candidate, Nb-doped Bi₂Se₃ through differential conductance spectroscopy and magneto-transport. The strong anisotropy of the critical field along the out-of-plane direction suggests that the thin exfoliated flakes are in the quasi-2D limit. Normal metal-superconductor (NS) contacts with either high or low transparencies made by depositing gold leads onto Nb-doped Bi₂Se₃ flakes both show significant enhancement in zero bias conductance and coherence dips at the superconducting energy gap. Such behavior is inconsistent with conventional Blonder–Tinkham–Klapwijk theory. Instead, we discuss how our results are consistent with p-wave pairing symmetry, supporting the possibility of topological superconductivity in Nb-doped Bi₂Se₃. Lastly, we observe signatures of multiple superconducting energy gaps, which could originate from multiple Fermi surfaces reported earlier in bulk crystals.

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Research Organization:: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Organization:: USDOE; National Science Foundation (NSF)

Grant/Contract Number:: DMR-1506152; HRD-1547830; DMR-1255607

OSTI ID:: 1543686

Journal Information:: Nano Letters, Vol. 19, Issue 1; ISSN 1530-6984

Publisher:: American Chemical SocietyCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 12 works

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36 MATERIALS SCIENCE
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Materials Science
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exfoliated NbxBi2Se3
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Title: Conductance Spectroscopy of Exfoliated Thin Flakes of NbxBi2Se3

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Title: Conductance Spectroscopy of Exfoliated Thin Flakes of Nb_xBi₂Se₃