### Abstract

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.

Original language | English |
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Article number | B08S90 |

Pages (from-to) | 1-13 |

Number of pages | 13 |

Journal | Journal of Geophysical Research |

Volume | 112 |

Issue number | B8 |

DOIs | |

Publication status | Published - 4 Aug 2007 |

Externally published | Yes |

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### Keywords

- FORC diagrams
- biogenic magnetic particles
- magnetostatic interaction

### Cite this

*Journal of Geophysical Research*,

*112*(B8), 1-13. [B08S90]. https://doi.org/10.1029/2006JB004575