Giant strain-induced ferromagnetism in Fe₅₉Mn₁₇Al₂₄

Abstract

Giant strain-induced ferromagnetism (SIF) has been observed in Fe₅₉Mn₁₇Al₂₄ single crystals. The crystals in either the L2₁ or B2 ordered state are weakly magnetic, with saturation magnetization, M _s, of 9–10 emu/g. After a 60% thickness reduction, the M _s of the L2₁ crystal increased to 89 emu/g, whereas the M _s of the B2 crystal after a 53% reduction was 96 emu/g, an M _s approximately four times larger than that of the largest SIF observed in other ordered alloys. By comparison, mechanically alloyed powder of the same composition, which had a fully-disordered bcc structure, showed a similar M _s of ∼90 emu/g. The increased M _s in strained Fe₅₉Mn₁₇Al₂₄ single crystals is attributed primarily to the generation of increased magnetic coupling due to chemical disordering. This large M _s is substantially reduced after annealing at 573 K.

Keywords:

• disorder
• intermetallics
• magnetic properties
• strain-induced ferromagnetism

Acknowledgements

This research was supported by National Science Foundation Grant DMR 0552380. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF or the U.S. Government.