Andreev Reflection in an s-Type Superconductor Proximized 3D Topological Insulator

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...

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Bibliographic Details
Published in:Physical review letters 2016-09, Vol.117 (14), p.147001-147001, Article 147001
Main Authors: Tikhonov, E S, Shovkun, D V, Snelder, M, Stehno, M P, Huang, Y, Golden, M S, Golubov, A A, Brinkman, A, Khrapai, V S
Format: Article
Language:English
Subjects:
Contact
Insulators
Magnetic fields
Reflection
Semiconductors
Shot noise
Topology
Transport
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Summary: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 F_{N}≈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 F_{AR}≈0.22±0.02 is considerably reduced in the AR regime compared to F_{N}, 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.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.117.147001