Ferromagnetic resonance spectra of magnetofossils in theory and practice

Abstract:

Intact magnetosome chains in whole cell samples of magnetotactic bacteria produce ferromagnetic resonance (FMR) spectra that are distinctively asymmetric. However, these usually do not match FMR spectra of sediments that contain a high percentage of magnetofossils. A possible reason for this discrepancy may be chain collapse, which perturbs the orientation of the easy axes and the chain axis. Alternatively, linear chains may be present in which a crystallographic easy axis (<111> for magnetite) is not oriented along the long particle axis and chain axis, as is the case in magnetotactic bacteria strains that do not produce particles of regular morphology and for which FMR data have not been recorded yet. Here I present forward computed FMR spectra for both scenarios and compare these with magnetofossil data.