Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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Ion irradiation induced local creation of ferromagnetism in Fe60Al40 alloysStrache, T.; Liedke, M. O.; Fassbender, J.ORC; Möller, W.; Menéndez, E.; Sort, J.; Suriñach, S.; Baró, M. D.; Gemming, T.; Weber, A.; Heyderman, L. 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. This proves the purely ballistic nature of the disordering process. 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. Comparing different noble gas ion irradiation experiments allows to asses the corresponding counteracting contributions. In addition, the potential to create local ferromagnetic areas embedded in a paramagnetic matrix is demonstrated.
Keywords: magnetism, ion irradiation, binary alloys, intermetallic, FIB, patterning
Ionenstrahlphysik und Nanotechnologie, GSI-Workshop, 11.-12.04.2008, Darmstadt, Germany