Anhysteretic remanent magnetization: model of grain size distribution of spherical magnetite grains

SOMACAL, AGUSTÍN; SAPIENZA, FACUNDO F.; VASQUEZ, CARLOS A.; FAZZITO, SABRINA

STUDIA GEOPHYSICA ET GEODAETICA

SPRINGER

Año: 2018 vol. 62 p. 339 - 351

0039-3169

A phenomenological model based on a linear relationship between the magnetic17 coercivity field and the reciprocal of the grain diameter was applied to explain the18 anhysteretic remanent magnetization (ARM) imparted to artificial samples with different19 concentrations of a very well characterized magnetite powder. By analyses of scanning20 electron microscopy images, the spherically shaped single domain synthetic magnetite21 was found to follow a lognormal grain size distribution with 86 nm of mean diameter.22 The proposed model, fitted to ARM measurements up to a peak alternating field of23 100 mT, yielded very good agreement. The coercivity behaviour predicted by24 micromagnetism theory disagrees with the experimental results of this work. A likely25 explanation for the discrepancy is that the magnetite particles, which consist of a mixture26 of grains in coherent rotation and curling modes, produce similar observations as domain27 processes.2829