Interstitial Fe-Cr alloys: tuning of magnetism by nanoscale structural control and by implantation of nonmagnetic atoms

Using the density functional theory, we perform a full atomic relaxation of the bulk ferrite with 12.5% concentration of monoatomic interstitial Cr periodically located at the edges of the bcc Feα cell. We show that structural relaxation in such artificially engineered alloys leads to significant atomic displacements and results in the formation of novel highly stable configurations with parallel chains of octahedrically arranged Fe. The enhanced magnetic polarization in the low-symmetry metallic state of this type of alloy can be externally controlled by additional inclusion of nonmagnetic impurities like nitrogen. We discuss possible applications of generated interstitial alloys in spintronic devices and propose to consider them as a basis of novel durable types of stainless steels