  Experimental evidence show that in the magnetoresistive manganite Ca_(1-x)
Y_xMnO_3, ferromagnetic (FM) polarons arises in an antiferromagnetic (AF)
background, as a result of the doping with Yttrium. This hypothesis is
supported in this work by classical Monte Carlo (MC) calculations performed on
a model where FM Double Exchange (DE) and AF Superexhange (SE) compite.
