Magnetic phase diagram simulation of La1−xCaxMnO3 system by using Monte Carlo, Metropolis algorithm and Heisenberg model

This work presents a critical temperature study of La1−xCaxMnO3 manganites in bulk by means of Monte Carlo method thermal activated magnetic properties. The analysis was carried out for stoichiometries in the range of 0≤x≤1. The model is based on a three-dimensional classical Heisenberg–Hamiltonian involving the presence of Mn3+eg, Mn3+eg′ and Mn4+ ions, and their nearest neighbor interaction. For this modeling, simple cubic lattice samples of size L3, with L=6, 15 and 30 were used. The values of exchange parameters were determined by using LaMnO3 (x=0), La0.5Ca0.5MnO3 and CaMnO3 (x=1) phases. Relationships between exchange parameters and anisotropy constants for different hole densities were found. Results of transition temperatures for each phase showed good agreement with experimental reports, especially for L=30 and L→∞.

Research highlights
► Stoichiometry influences the exchange interaction between magnetic ions.
► Charge and orbital ordering depend on the stoichiometry.
► LCMO magnetic phase diagram has a great variety of magnetic states.