Jan Smotlacha: Andreev reflection in Weyl semimetals

Weyl semimetals are a new subject in the field of condensed matter physics. In the comparison with the normal semimetals, they are characteristic by a non-trivial topological structure, where 2 disconected sheets of the Fermi surface enclose a pair of degeneracy points called Weyl nodes.

We give a brief review into these materials and related phenomena and then we focus our attention on the transport properties of sandwiched structures consisting of different parts which can correspond to normal metal, Weyl semimetal or metallic superconductor. An important role plays here the process of the penetration of a Cooper pair into the Weyl semimetal – the Andreev reflection. We distinguish between the Weyl semimetals of the first and second kind. Among others, the difference between both structures is given by their reflection properties: in the second material, double Andreev reflection occurs. We study the dependence of the conductance on a uniform magnetic field acting in different directions.

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