Andreev reflection in Euler materials

Abstract

Many previous studies of Andreev reflection have demonstrated that unusual effects can occur in media which have a nontrivial bulk topology. Following this line of investigation, we study Andreev reflection in topological Euler materials by analysing a simple model of a bulk node with a generic winding number $n\geq 0$. We find that the magnitudes of the resultant reflection coefficients depend strongly on whether the winding is even or odd. Moreover this parity dependence is reflected in the differential conductance curves, which are highly suppressed for $n$ even but not $n$ odd. This gives a possible route through which the recently discovered Euler topology could be probed experimentally.