Ion mass dependence of the irradiation induced local creation of ferromagnetism in Fe60Al40 alloys
Ion mass dependence of the irradiation induced local creation of ferromagnetism in Fe60Al40 alloys
Fassbender, J.; Liedke, M. O.; Strache, T.; Möller, W.; Menendez, E.; Sort, J.; Rao, K. V.; Deevi, S. C.; Nogues, J.
Ion irradiation of Fe60Al40 alloys results in the phase transformation from the paramagnetic, chemically ordered B2-phase to the ferromagnetic, chemically disordered A2-phase. The magnetic phase transformation is related to the number of displacements per atom (dpa) during the irradiation. For heavy ions (Ar+, Kr+, Xe+) a universal curve is observed with a steep increase in the fraction of ferromagnetic phase reaching saturation, i. e., a complete phase transformation, at about 0.5 dpa. However, already less than 0.05 dpa are sufficient to create significant ferromagnetism without a change of surface topography. If light ions are used (He+, Ne+) a pronounced deviation from the universal curve is observed. This is attributed to bulk vacancy diffusion from dilute collision cascades, which leads to a partial recovery of the thermodynamically favored B2-phase. In any case the initial paramagnetic state can be restored by annealing the samples to 800 K. In addition, the potential to create local ferromagnetic areas embedded in a paramagnetic matrix is demonstrated.
Keywords: magnetism; ion irradiation; phase transformation; intermetallic alloys
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Physical Review B 77(2008), 174430
DOI: 10.1103/PhysRevB.77.174430
Cited 36 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-10432