Transition metal impurity effect on charge and spin density in iron: Ab initio calculations and comparison with M\"{o}ssbauer data

TL;DR

This study uses ab initio density functional theory to analyze how various d impurities and gallium affect charge and spin densities in alpha-iron, correlating computational results with Moessbauer spectroscopy data.

Contribution

It provides detailed ab initio calculations of impurity effects on hyperfine interactions in iron and compares these with experimental Moessbauer data, offering parameters for spectrum analysis.

Findings

Impurities influence charge and spin densities up to second or third coordination shells.

Hyperfine parameters are affected by volume mismatch and electron band mixing.

Parameters enable interpretation of Moessbauer spectra for impurity concentration and order.

Abstract

Density functional theory was applied to study influence of the isolated impurity located on the regular site of the alpha-Fe crystal on the charge and spin density (hyperfine interactions) on the iron nucleus. Calculations were performed by using both pseudopotential and the full potential methods. The scalar relativistic approximation was applied. Perturbations of the charge and spin density on iron were calculated for all d impurities soluble in iron and additionally for Ga impurity. It was found that impurities have measurable effect on the iron charge and spin density up to the second or third coordination shell depending on the impurity. Hyperfine parameters of iron adjacent to the impurity are affected by two intermixed physical mechanisms, i.e., the volume mismatch due to the impurity and electron band mixing caused by the electronic configuration of the impurity outer shells. Some correlations between ab initio calculations and Moessbauer experimental results are discussed. A table is provided with the parameters allowing calculate Moessbauer spectrum of the binary iron alloy with d impurity or Ga. On the other hand, provided parameters allow extraction from the Moessbauer data information about impurity concentration and eventual order.