We study the differential conductance of a time-reversal symmetric Weyl semimetal-superconductor junction with an $s$-wave superconducting state. We find that there exists an extended regime where the zero-bias differential conductance acquires the universal value of $e^2/h$ per 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.

• Received 22 November 2017

DOI:https://doi.org/10.1103/PhysRevB.97.041116