  The 2D ferromagnetic Kondo model with classical corespins is studied for a
hole doping up to x = 0.125 via unbiased Monte Carlo (MC) simulations. A
canonical algorithm for finite temperatures is developed.
  We show that with realistic parameters for the manganites and at low
temperatures, the double-exchange mechanism does not lead to phase separation
on a two-dimensional lattice but rather stabilizes individual ferromagnetic
polarons. A detailed analysis of unbiased MC results reveals that the polarons
can be treated as independent particles.
  It is found that a simple polaron model perfectly describes the physics of
the FM Kondo model. The ferromagnetic polaron picture provides an obvious
explanation for the pseudogap in the one-particle spectral function
$A_k(\omega)$ observed in the FM Kondo model.
