Monte Carlo simulations of magnetic order in Fe-doped manganites

摘要

The effect of Fe doping on the magnetic properties of La0.7Pb0.3Mn1-xFexO3 (x = 0, 0.05, 0.1, 0.15 and 0.2) manganites is studied by the Monte Carlo simulation technique. As a first approximation, by means of a simple Heisenberg Hamiltonian, experimental normalized magnetizations at low temperatures have been reproduced for concentrations of Fe (x < 0.2), but the calculated order temperatures show a large deviation from the measured ones. This shortcoming can be corrected by using a one electron effective hopping semi-classical Hamiltonian, with a simplified expression for the kinetic energy of the free electrons, which also avoids time-consuming diagonalizations. (c) 2007 Elsevier B.V. All rights reserved.