Auger recombination (AR) being electron-hole annihilation with energy-momentum transfer to another carrier is believed to speed up in materials with small band gap. We theoretically show that this rule is violated in gapless three-dimensional materials with ultrarelativistic electron-hole dispersion, Weyl semimetals (WSMs). Namely, AR is prohibited by energy-momentum conservation laws in prototypical WSM with a single Weyl node, even in the presence of anisotropy and tilt. In real multinode WSMs, the geometric dissimilarity of nodal dispersions enables weak internode AR, which is further suppressed by strong screening due to large number of nodes. While partial AR rates between the nodes of the same node group are mutually equal, the intergroup processes are nonreciprocal, so that one of the groups is geometrically protected from AR. This geometrical protection prolongs AR lifetime up to two orders of magnitude, to the level of nanoseconds.

• Received 13 November 2018

DOI:https://doi.org/10.1103/PhysRevB.99.115202