The mössbauer spectra of substituted systems local molecular field theory

An insulator with two different magnetic ions distributed in several crystallographic sites is considered in the molecular field approximation. As an example a material containing a random distribution of iron and a non‐magnetic ion in equivalent sites is studied, assuming that the superexchange between an iron ion and cations on six nearest‐neighbour sites is the dominant interaction. Provided that a small longer range interaction is present, the Mössbauer spectra predicted for different non‐magnetic concentrations at various temperatures are in agreement with experimental observation except just below the magnetic ordering temperature.