Superferromagnetism

Superferromagnetism is the magnetism of an ensemble of magnetically interacting super-moment-bearing material particles that would be superparamagnetic if they were not interacting.[1] Nanoparticles of iron oxides, such as ferrihydrite (nominally FeOOH), often cluster and interact magnetically. These interactions change the magnetic behaviours of the nanoparticles (both above and below their blocking temperatures) and lead to an ordered low-temperature phase with non-randomly oriented particle super-moments.

Discovery

The phenomenon appears to have been first described and the term "superferromagnatism" introduced by Bostanjoglo and Röhkel, for a metallic film system.[2] A decade later, the same phenomenon was rediscovered and described to occur in small-particle systems.[3][4] The discovery is attributed as such in the scientific literature.[5]

References
  1. Rancourt, D. G. (2001-01-01). "Magnetism of Earth, Planetary, and Environmental Nanomaterials". Reviews in Mineralogy and Geochemistry. 44 (1): 217–292. Bibcode:2001RvMG...44..217R. doi:10.2138/rmg.2001.44.07. ISSN 1529-6466.
  2. Bostanjoglo, O.; Röhkel, K. (1972-05-16). "Superferromagnetism in gadolinium films". Physica Status Solidi A. 11 (1): 161–166. Bibcode:1972PSSAR..11..161B. doi:10.1002/pssa.2210110117. ISSN 0031-8965.
  3. Mørup, Steen; Bo Madsen, Morten; Franck, Jørgen; Villadsen, Jørgen; Koch, Christian J.W. (1983). "A new interpretation of Mössbauer spectra of microcrystalline goethite: "Super-ferromagnetism" or "super-spin-glass" behaviour?". Journal of Magnetism and Magnetic Materials. 40 (1–2): 163–174. Bibcode:1983JMMM...40..163M. doi:10.1016/0304-8853(83)90024-0. ISSN 0304-8853.
  4. Rancourt, D. G.; Daniels, J. M. (1984-03-01). "Influence of unequal magnetization direction probabilities on the Mössbauer spectra of superparamagnetic particles". Physical Review B. 29 (5): 2410–2414. Bibcode:1984PhRvB..29.2410R. doi:10.1103/physrevb.29.2410. ISSN 0163-1829.
  5. Bedanta, S.; Seki, T.; Iwama, H.; Shima, T.; Takanashi, K. (2015-10-12). "Superferromagnetism in dipolarly coupled FePt nanodots with perpendicular magnetization". Applied Physics Letters. 107 (15): 152410. doi:10.1063/1.4933381. ISSN 0003-6951.


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