Novel insights from an atomic-scale study of defects leading to enhanced magnetization in CoFeCrAl

Abstract

Novel insights into the local structural ordering/disordering at the atomic scale in CoFeCrAl, which might have significant implications for the magnetic exchange interactions and hence spintronic applications, have been deduced in the present study. Insights on the importance of Co–Fe, Fe–Cr and Fe–Al magnetic exchange interactions are presented based on the linear variation of magnetic hyperfine fields at Fe sites in some Heusler compounds containing Co, Fe, Cr and Al with increasing electron valence in accordance with the Slater–Pauling rule. Atomic-scale understanding of the defects resulting in enhanced hyperfine fields at the Fe sites in CoFeCrAl is deduced and compared with that in Co₂Fe_0.5Cr_0.5Al, an analogous full-Heusler compound. The results of this study might have significant implications for fine-tuning the defects, leading to enhanced magnetization while retaining the bulk structural ordering in CoFeCrAl, which would be highly useful for realizing spintronic devices, such as magnetic tunnel junctions and spin valves, with appreciably enhanced spin polarization efficiency.