  The remarkable gapless and linear band structure of graphene opens up new
carrier relaxation channels bridging the valence and the conduction band. These
Auger scattering processes change the number of charge carriers and can give
rise to a significant multiplication of optically excited carriers in graphene.
This is an ultrafast many-particle phenomenon that is of great interest both
for fundamental many-particle physics as well as technological applications.
Here, we review the research on carrier multiplication in graphene and
Landau-quantized graphene including theoretical modelling and experimental
demonstration.
