Effect of Cr and Mn ions on the structure and magnetic properties of GaFeO 3: Role of the substitution site

Abstract

Effect of substitution of Cr and Mn in the Fe and Ga sites of GaFeO 3 on the structural parameters and magnetic properties has been investigated by preparing GaFe 1− x Cr x (Mn x )O 3 and Ga 1− x Cr x (Mn x )FeO 3 starting with appropriate oxide precursors. It is shown that, starting with Cr or Mn substituted Ga 2O 3, one obtains Ga 1− x Cr x (Mn x )FeO 3, while reaction of Cr or Mn substituted α-Fe 2O 3 with Ga 2O 3 yields GaFe 1− x Cr x (Mn x )O 3. The structural parameters and magnetic properties vary significantly with the substitution site of Cr showing a large decrease in the unit cell parameters as well as the T C and other magnetic properties when the substitution is at the octahedral Fe (1, 2) site. Substitution of Cr at the octahedral Ga2 site results in marginal changes. Substitution of Mn in the Ga and Fe sites also show differences although the changes themselves are much smaller. First-principles calculations confirm such site-specificity and show how Cr substitution affects the properties differently when substituted at the Ga2 and Fe1 sites.