Open AccessFirst‐order reversal curve (FORC) diagrams of natural and cultured biogenic magnetic particles
Author(s) -
Chen Amy P.,
Egli Ramon,
Moskowitz Bruce M.
Publication year - 2007
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006jb004575
Subject(s) - magnetosome , interpretation (philosophy) , magnetotactic bacteria , condensed matter physics , physics , diagram , single domain , domain (mathematical analysis) , coercivity , magnetization , magnetic domain , materials science , magnetic field , magnetite , statistics , mathematics , quantum mechanics , mathematical analysis , computer science , metallurgy , programming language
First‐order reversal curve (FORC) diagrams are rapidly becoming a standard tool for characterizing magnetic particles because they simultaneously incorporate information regarding magnetostatic interaction and domain states. The simplest interpretation of FORC diagrams of single‐domain (SD) particles is based on the Neel interpretation of Preisach theory, which predicts that the FORC function is the product of a coercivity and an interaction field distribution. Although the underlying assumptions of this interpretation are not correct, a strictly quantitative model of weakly interacting SD grains proves that the distributions of coercivities and interaction fields can be retrieved from a FORC diagram. To test this model, we present the possibility of a quantitative interpretation of FORC diagrams, and we present measurements of samples containing magnetosomes from cultures of magnetotactic bacteria and from a lake sediment. Two samples are investigated under the electron microscope to characterize the geometrical arrangement of the particles. We find that the clustering of otherwise similar particles has a strong influence on FORC diagrams. We also obtained a crude estimate of packing densities form the FORC diagrams, which were consistent with transmission electron microscopy observations and measurements of the anhysteretic remanent magnetization.