Slow Magnetic Relaxation in Iron: A Ferromagnetic Liquid

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Science  21 May 1993:
Vol. 260, Issue 5111, pp. 1098-1101
DOI: 10.1126/science.260.5111.1098


The remanent magnetization of single-crystal iron whiskers has been measured from 10-5 to 104 seconds after the removal of an applied field. The observed response is accurately modeled by localized magnon relaxation on a Gaussian size distribution of dynamically correlated domains, virtually identical to the distribution of excitations in glass-forming liquids. When fields of less than 1 oersted are removed, some relaxation occurs before 10-5 second has elapsed; but when larger fields are removed, essentially all of the response can be accounted for by magnon relaxation over the available time window. The model provides a physical picture for the mechanism and observed distribution of Landau-Lifshitz damping parameters.