Parameterisation of non-collinear energy landscapes in itinerant magnets

The magnetic force theorem provides convenient ways to study exchange interactions in magnetic systems. However, it is well known that short range interactions in itinerant magnetic systems are poorly described with the conventional use of the theorem and numerous strategies have been developed over the years to overcome this deficiency. In this study, we discuss this issue in the context of the frozen magnon method and find that a self-consistent approach is in general preferable. Moreover, an extended Heisenberg model is suggested in order to better describe finite deviations from the magnetic ground state and is shown through cross-validation to give a superior description of the interactions in non-collinear magnetic configurations compared to the regular Heisenberg model. The present study thus supplies a fully self-consistent method for systematic investigations of exchange interactions beyond the standard Heisenberg model. This may prove relevant to high-throughput computational materials science, e.g., in developing high moment materials for the magnetic storage industry.