EGU25-10133, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-10133
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
PSD: Possibly Single Domain?
Brendan Cych1, Greig Paterson1, Lesleis Nagy1, and Wyn Williams2
Brendan Cych et al.
  • 1University of Liverpool, Earth, Ocean and Ecological Sciences, Liverpool, United Kingdom of Great Britain – England, Scotland, Wales (bcych@liverpool.ac.uk)
  • 2University of Edinburgh, Geosciences, Edinburgh, United Kingdom of Great Britain - England, Scotland, Wales

Néel's theory of single domain magnetizations has been widely applied in paleomagnetism since its conception in the 1940s. When applying this theory, paleomagnetists typically assume that all magnetic particles are composed of magnetite, and are shaped like highly elongate needles. Even in the SD size range, natural samples exhibit a much wider range of morphologies, causing a gap between theory and experiments. Although these assumptions were necessary in the 1940s, computing power today means they are no longer required.

 

To understand the behaviour of other types of SD particles, we have created a new software package called the Single Domain Comprehensive Calculator (SDCC). The SDCC can derive the magnetic properties of SD particles from first principles, without making the assumptions of Néel. The package provides a simple python scripting interface to simulate almost any paleomagnetic experiments, with assemblages of particles of different sizes, shapes and compositions.

 

Simulations with the SDCC show that single domain particles exhibit a much wider range of experimental behaviour than has previously been discussed. In particular, we show that the relationship between blocking temperature and relaxation time is strongly dependent on the shape and composition of the particle. This causes viscously acquired remanences to unblock over a wide range of temperatures on laboratory timescales. To demonstrate this, we ran a simulation where an assemblage of SD particles acquired a viscous overprint over a primary thermal remanence. On simulated thermal demagnetization, the two magnetizations exhibited overlapping unblocking spectra, which would lead to problematic behaviour in paleomagnetic experiments.

How to cite: Cych, B., Paterson, G., Nagy, L., and Williams, W.: PSD: Possibly Single Domain?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10133, https://doi.org/10.5194/egusphere-egu25-10133, 2025.