Monte Carlo simulations applied to a model of interacting fermions and clas
sical spins show the existence of antiferromagnetic spin domains and charge
stripes upon hole doping. The stripes have a filling of approximately 1/2
hole per site, and they separate spin domains with a pi phase shift among t
hem. The observed stripes run either along the x or y axes. No particular b
oundary conditions or external fields are needed to stabilize these structu
res. When magnetic incommensurate peaks are observed at momentum pi(1, 1 -
delta), charge incommensurate peaks appear at (0, 2 delta). The charge fluc
tuations responible for the stripe formation also induce a pseudogap in the
density of states.