MI2023 - 09 Wyn Williams: Shedding Light on Vortex Behaviour in the Day Diagram
Channel: MagNetZ
Date: 2023-01-16

Magnetic Interactions 2023 conference at the University of Cambridge
Session 2: Rock and Mineral Magnetism

Title: From Night to Day: Shedding Light on Vortex Behaviour in the Day Diagram
Author: Wyn Williams from the University of Edinburgh, UK

The ability of rocks to hold a reliable record of the ancient geomagnetic field depends on the structure and stability of magnetic domain-states contained within the rocks' magnetic mineral grains. In paleomagnetic studies the Day plot is an easily constructed graph of magnetic hysteresis parameters that are frequently used to estimate the likely recording stability of samples. Often samples plot in the region of the Day plot attributed to pseudosingle-domain (PSD) grains with little understanding of the implication of domain-states or recording fidelity. Here we use micromagnetic models to explore the hysteresis parameters of magnetite grains with idealized grain prolate and oblate cuboctahedral geometries. We show these form a well-defined trend in the in Day plot that extends from the SD region well into the MD, all of which are likely to be stable remanence carriers. We suggest that Day plots and their variants can still provide a useful discriminator of stable magnetic recorders, and if the magnetic mineralogy is known, Day plots and its variants may be used to estimate the stability of paleomagnetic specimens' domain states and grain sizes.

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00:00 - Intro
00:30 - Presentation
15:40 - Questions