Andreev reflection in an s-type superconductor proximized 3D topological insulator

E.S. Tikhonov, D.V. Shovkun, M. Snelder, M.P. Stehno, Y. Huang, M.S. Golden, A.A. Golubov, A. Brinkman, V.S. Khrapai

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Abstract

We investigate transport and shot noise in lateral normal-metal–3D topological-insulator–superconductor contacts, where the 3D topological insulator (TI) is based on Bi. In the normal state, the devices are in the elastic diffusive transport regime, as demonstrated by a nearly universal value of the shot noise Fano factor FN≈1/3 in magnetic field and in a reference normal-metal contact. In the absence of magnetic field, we identify the Andreev reflection (AR) regime, which gives rise to the effective charge doubling in shot noise measurements. Surprisingly, the Fano factor FAR≈0.22±0.02 is considerably reduced in the AR regime compared to FN, in contrast to previous AR experiments in normal metals and semiconductors. We suggest that this effect is related to a finite thermal conduction of the proximized, superconducting TI owing to a residual density of states at low energies.
Original languageEnglish
Article number147001
Number of pages5
JournalPhysical review letters
Volume117
Issue number14
DOIs
Publication statusPublished - 2016

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shot noise
insulators
noise measurement
magnetic fields
metals
electric contacts
conduction
energy

Keywords

  • METIS-319301
  • IR-103834

Cite this

Tikhonov, E. S., Shovkun, D. V., Snelder, M., Stehno, M. P., Huang, Y., Golden, M. S., ... Khrapai, V. S. (2016). Andreev reflection in an s-type superconductor proximized 3D topological insulator. Physical review letters, 117(14), [147001]. https://doi.org/10.1103/PhysRevLett.117.147001
Tikhonov, E.S. ; Shovkun, D.V. ; Snelder, M. ; Stehno, M.P. ; Huang, Y. ; Golden, M.S. ; Golubov, A.A. ; Brinkman, A. ; Khrapai, V.S. / Andreev reflection in an s-type superconductor proximized 3D topological insulator. In: Physical review letters. 2016 ; Vol. 117, No. 14.
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Tikhonov, ES, Shovkun, DV, Snelder, M, Stehno, MP, Huang, Y, Golden, MS, Golubov, AA, Brinkman, A & Khrapai, VS 2016, 'Andreev reflection in an s-type superconductor proximized 3D topological insulator' Physical review letters, vol. 117, no. 14, 147001. https://doi.org/10.1103/PhysRevLett.117.147001

Andreev reflection in an s-type superconductor proximized 3D topological insulator. / Tikhonov, E.S.; Shovkun, D.V.; Snelder, M.; Stehno, M.P.; Huang, Y.; Golden, M.S.; Golubov, A.A.; Brinkman, A.; Khrapai, V.S.

In: Physical review letters, Vol. 117, No. 14, 147001, 2016.

Research output: Contribution to journalArticleAcademicpeer-review

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T1 - Andreev reflection in an s-type superconductor proximized 3D topological insulator

AU - Tikhonov, E.S.

AU - Shovkun, D.V.

AU - Snelder, M.

AU - Stehno, M.P.

AU - Huang, Y.

AU - Golden, M.S.

AU - Golubov, A.A.

AU - Brinkman, A.

AU - Khrapai, V.S.

PY - 2016

Y1 - 2016

N2 - We investigate transport and shot noise in lateral normal-metal–3D topological-insulator–superconductor contacts, where the 3D topological insulator (TI) is based on Bi. In the normal state, the devices are in the elastic diffusive transport regime, as demonstrated by a nearly universal value of the shot noise Fano factor FN≈1/3 in magnetic field and in a reference normal-metal contact. In the absence of magnetic field, we identify the Andreev reflection (AR) regime, which gives rise to the effective charge doubling in shot noise measurements. Surprisingly, the Fano factor FAR≈0.22±0.02 is considerably reduced in the AR regime compared to FN, in contrast to previous AR experiments in normal metals and semiconductors. We suggest that this effect is related to a finite thermal conduction of the proximized, superconducting TI owing to a residual density of states at low energies.

AB - We investigate transport and shot noise in lateral normal-metal–3D topological-insulator–superconductor contacts, where the 3D topological insulator (TI) is based on Bi. In the normal state, the devices are in the elastic diffusive transport regime, as demonstrated by a nearly universal value of the shot noise Fano factor FN≈1/3 in magnetic field and in a reference normal-metal contact. In the absence of magnetic field, we identify the Andreev reflection (AR) regime, which gives rise to the effective charge doubling in shot noise measurements. Surprisingly, the Fano factor FAR≈0.22±0.02 is considerably reduced in the AR regime compared to FN, in contrast to previous AR experiments in normal metals and semiconductors. We suggest that this effect is related to a finite thermal conduction of the proximized, superconducting TI owing to a residual density of states at low energies.

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