Correlation Strength Crossover of Auger Recombination in One-Dimensional Mott Insulators

We theoretically investigate the relaxation of photogenerated charge carriers in one-dimensional Mott insulators. We adopt the Pariser-Parr-Pople model, and numerically calculate the time development of the nonequilibrium state excited by a weak light pulse. We investigate the dependence of the dynamics on the Coulomb correlation strength in the case where the binding effect between photogenerated opposite charges is significant. In the strong-correlation region (U >> W), where U is the onsite Coulomb interaction energy and W is the bandwidth, the Auger recombination where two bound holon-doublon pairs decay into one unbound holon-doublon pair dominates the decay dynamics. From the strong- to intermediate (U approximately equal to W)-correlation regions, the Auger recombination is always dominant, but the charge carriers involved in the process cannot be described by a holon and a doublon in the intermediate-correlation region. In the crossover region between these two regions, the Auger coefficient is strongly enhanced, and the decay time constant is consistent with those obtained in recent experiments.