Modeling of the magnetic free energy of self-diffusion in bcc Fe
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 18, 184102Article in journal (Refereed) Published
A first-principles based approach to calculating self-diffusion rates in bcc Fe is discussed with particular focus on the magnetic free energy associated with diffusion activation. First, the enthalpies and entropies of vacancy formation and migration in ferromagnetic bcc Fe are calculated from standard density functional theory methods in combination with transition state theory. Next, the shift in diffusion activation energy when going from the ferromagnetic to the paramagnetic state is estimated by averaging over random spin states. Classical and quantum mechanical Monte Carlo simulations within the Heisenberg model are used to study the effect of spin disordering on the vacancy formation and migration free energy. Finally, a quasiempirical model of the magnetic contribution to the diffusion activation free energy is applied in order to connect the current first-principles results to experimental data. The importance of the zero-point magnon energy in modeling of diffusion in bcc Fe is stressed.
Place, publisher, year, edition, pages
American Physical Society , 2015. Vol. 92, no 18, 184102
Condensed Matter Physics
IdentifiersURN: urn:nbn:se:kth:diva-177936DOI: 10.1103/PhysRevB.92.184102ISI: 000364214000003ScopusID: 2-s2.0-84948462023OAI: oai:DiVA.org:kth-177936DiVA: diva2:876366
QC 201512032015-12-032015-11-302015-12-03Bibliographically approved