Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 57: Topological Semimetals III

TT 57.3: Vortrag

Mittwoch, 14. März 2018, 10:30–10:45, A 053

Appearance of the universal value e²/h of the zero-bias conductance in a Weyl semimetal-superconductor junction — Songbo Zhang¹, •Fabrizio Dolcini², Daniel Breunig¹, and Björn Trauzettel¹ — ¹Institute for Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany — ²Dipartimento di Scienza Applicata e Tecnologia del Politecnico di Torino, I-10129 Torino, Italy

We study the differential conductance of a time-reversal symmetric Weyl semimetal-superconductor (N-S) junction with an s-wave superconducting state. We find that there exists an accessible regime where the zero-bias differential conductance acquires the universal value e²/h per unit channel, independent of the pairing and chemical potentials on each side of the junction, due to a perfect cancellation of Andreev and normal reflection contributions. This universal conductance can be attributed to the interplay of the unique spin/orbital-momentum locking and s-wave pairing that couples Weyl nodes of the same chirality. We expect that the universal conductance can serve as a robust and distinct signature for time-reversal symmetric Weyl fermions, and be observed in the recently discovered time-reversal symmetric Weyl semimetals.