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P. Werner, K. Held, M. Eckstein:
"Role of impact ionization in the thermalization of photoexcited Mott insulators";
Physical Review B, 90 (2014), 235102.

We study the influence of the pulse energy and fluence on the thermalization of photodoped Mott insulators. If
theMott gap is smaller than the width of the Hubbard bands, the kinetic energy of individual carriers can be large
enough to produce additional doublon-hole pairs via a process analogous to impact ionization. The thermalization
dynamics, which involves an adjustment of the doublon and hole densities, thus changes as a function of the
energy of the photo-doped carriers and exhibits two time scales: a fast relaxation related to the impact ionization
of high-energy carriers and a slower time scale associated with higher-order scattering processes. The slow
dynamics depends more strongly on the gap size and the photodoping concentration.

http://dx.doi.org/10.1103/PhysRevB.90.235102