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MM: Fachverband Metall- und Materialphysik

MM 39: Computational Materials Modelling - Alloys I

MM 39.1: Vortrag

Mittwoch, 18. März 2020, 15:45–16:00, BAR 205

Atomistic spin dynamics coupled with ab initio molecular dynamics simulations of Fe in the paramagnetic state — •Davide Gambino and Björn Alling — Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, Sweden

Accurate investigation of magnetic materials at finite temperatures with first principles methods is a formidable task that requires inclusion of magnetic and vibrational effects on a similar footing in order to account for their interplay. An approach that allows to investigate the coupling of these different degrees of freedom is the atomistic spin dynamics - ab initio molecular dynamics (ASD-AIMD) method [Stockem et al., Physical Review Letters 121, 125902 (2018)], in which an AIMD and an ASD simulations are run in parallel communicating to each other atomic positions (which affect exchange interactions) and magnetic moments directions.

While the method was initially tested on CrN, a semiconducting system with well localized magnetic moments, in this work we perform an ASD-AIMD investigation of Fe in the paramagnetic state, close to its Curie temperature. Since Fe is a ferromagnetic metal, it is relevant to investigate also the contribution of longitudinal spin fluctuations (LSF) to the thermodynamics of the system. LSF are here included through a mean-field term derived from a semiclassical model. The present results pave the way for free-energy calculations in magnetic materials by means of ab initio methods.