Ferromagnetic Polarons in Manganites
  Using the Lanczos method in linear chains we study the double exchange model in the low concentration limit, including an antiferromagnetic super-exchange K. In the strong coupling limit we find that the ground state contains ferromagnetic polarons whose length is very sensitive to the value of K/t. We investigate the dispersion relation, the trapping by impurities, and the interaction between these polarons. As the overlap between polarons increases, by decreasing K/t, the effective interaction between them changes from antiferromagnetic to ferromagnetic. The scaling to the thermodynamic limit suggests an attractive interaction in the strong coupling regime (J_h > t) and no binding in the weak limit (J_h \simeq t). 
C.D. Batista (1), J. Eroles (1,2), M. Avignon (3) and B. Alascio (1)   ((1) Centro Atomico Bariloche, Argentina, (2) Los Ala...