Magnetism and local distortions near carbon impurity in $\gamma$-iron

TL;DR

This study uses ab initio calculations to explore how carbon impurities induce local ferromagnetic regions and distortions in gamma-iron, affecting magnetic and structural properties.

Contribution

It provides detailed insights into local magnetic and structural distortions caused by carbon impurities in gamma-iron, with calculated exchange integrals and solution enthalpy aligning well with experimental data.

Findings

Carbon creates ferromagnetic regions near impurities.

Substantial tetragonal distortions are observed.

Calculated solution enthalpy agrees with experiments.

Abstract

Local perturbations of crystal and magnetic structure of $\gamma$-iron near carbon interstitial impurity is investigated by {\it ab initio} electronic structure calculations. It is shown that the carbon impurity creates locally a region of ferromagnetic ordering with substantial tetragonal distortions. Exchange integrals and solution enthalpy are calculated, the latter being in a very good agreement with experimental data. Effect of the local distortions on the carbon-carbon interactions in $\gamma$-iron is discussed.