Publication details

First-principles study of magnetism at grain boundaries in iron and nickel


ČÁK Miroslav ŠOB Mojmír HAFNER J.

Year of publication 2008
Type Article in Periodical
Magazine / Source Physical Review B
MU Faculty or unit

Faculty of Science

Field Solid matter physics and magnetism
Keywords electronic structure; grain boundaries; magnetism
Description The geometric and magnetic structures of fully relaxed symmetrical tilt Sigma5(310) grain boundaries (GBs) in iron and Sigma5(210) GBs in nickel have been investigated using density-functional theory. We found for both GBs an enhancement of the local magnetic moments of atoms in the GB plane (2.55 mu_B for iron and 0.67 mu_B for nickel) which is correlated with the larger local atomic volume compared to the bulk. At larger distances from the GB the variation of the local magnetic moments follows the changes in the exchange splitting in the spin-polarized local density of states imposed by the local variations in the atomic geometry. When Si and Sn impurity atoms in interstitial or substitutional positions appear at the Sigma 5(310) GB in iron, the local magnetic moments of iron atoms are reduced for silicon and almost unchanged for tin.We also calculated the segregation enthalpies of both impurities and confirmed the experimental fact that silicon is a substitutional and tin an interstitial segregant; the calculated values of segregation enthalpy are in good agreement with experiment.
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