Institute

Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C)

The oldest magnetic record in our solar system identified

March 2018

by Jay Shah, Wyn Williams, Trevor P Almeida, Lesleis Nagy, Adrian R Muxworthy, András Kovács, Miguel A Valdez-Grijalva, Karl Fabian, Sara S Russell, Matthew J Genge and Rafal E Dunin-Borkowski

Recordings of magnetic fields, thought to be crucial to our solar system’s rapid accretion, are potentially retained in unaltered nanometric low-Ni kamacite grains encased within dusty olivine crystals, found in the chondrules of unequilibrated chondrites. However, most of these kamacite grains are magnetically non-uniform, so their ability to retain four-billion-year-old magnetic recordings cannot be estimated by previous theories, which assume only uniform magnetisation.

Here, researchers from Germany, Norway and the United Kingdom demonstrate that non-uniformly magnetised nanometric kamacite grains are stable over solar system timescales and likely the primary carrier of remanence in dusty olivine. By performing in-situ temperature-dependent nanometric magnetic measurements using off-axis electron holography, the thermal stability of multi-vortex kamacite grains from the chondritic Bishunpur meteorite is demonstrated. Combined with numerical micromagnetic modelling, the stability of the magnetisation of these grains is determined. The study shows that dusty olivine kamacite grains are capable of retaining magnetic recordings from the accreting solar system.