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# Andreev reflection and shot noise in a diffusive 3D topological insulator proximized by a superconductor

Name
Evgeny
Surname
Tikhonov
Scientific organization
MIPT, ISSP RAS
Position
junior researcher
Scientific discipline
Physics & Astronomy
Topic
Andreev reflection and shot noise in a diffusive 3D topological insulator proximized by a superconductor
Abstract
We experimentally study transport and shot noise in lateral N-TI-N and N-TI-S contacts defined on thin flakes of three-dimensional topological insulator Bi1.5Sb0.5Te1.7Se1.3 (N - normal metal, S - s-type superconductor). Via shot noise measurements we demonstrate the elastic diffusive transport regime in both N-TI-S contacts, subjected to the perpendicular magnetic field, and in N-TI-N contacts. In zero magnetic field, we show the Andreev reflection regime in N-TI-S contacts. Our measurements allow to extract the value of a proximity induced gap in the range ~0.3meV.
Keywords
topological insulator, superconductivity, andreev reflection
Summary

1) Intro;

2) Sample layout:

3) Magnetotransport data;

4) Shot noise and transport in the N-TI-N device: diffusive transport evidenced by the universal value of the Fano-factor $$F_{\mathrm{N}}\approx1/3$$;

5) Shot noise and transport in N-TI-S devices: effective charge doubling and the Fano-factor $$F_{\mathrm{AR}}\approx0.22\pm0.02$$ in zero magnetic field; diffusive transport and the Fano-factor $$F_{\mathrm{N}}\approx1/3$$ in magnetic field;

6) Finite bias 2e$$\to$$e transition and proximity gap extraction