Many applications of magnetic materials, e.g. Fe-based alloys, take place in the paramagnetic regime above the critical ordering temperature. Furthermore, even when low temperature applications are intended, the materials are typically synthesized in the paramagnetic regime. For these reasons it is valuable to obtain a theoretical methodology for modeling the paramagnetic phase of magnetic materials from first principles. This is a formidable challenge due to the simultaneous presence of magnetic, vibrational, electronic and structural excitations and disorder. In this presentation I will discuss recent methodological development that we have performed of several supercell-based implementations of disordered local moments (DLM) DFT-calculations suitable to address complex materials science problems.
In particular I will demonstrate results obtained with DLM-molecular dynamics (DLM-MD) where the effects of lattice vibrations on e.g. magnetic, and electronic structure of paramagnetic Fe can be directly observed. It is shown that at the high temperature of the gamma-delta transition in Fe, vibrations and magnetic disorder almost completely remove the differences in local magnetic moments and electronic density of states between the FCC and BCC structures. I will also show results of simulations of properties and phase stability in the important paramagnetic hard coating material CrN.
Department of Physics, Chemistry and Biology (IFM) – Linköpings Universitet