Nanomagnetic properties of the meteorite cloudy zone

Area of Science:

• * Planetary Science
• * Materials Science
• * Geophysics

Background:

• * Meteorites preserve thermal and magnetic histories through mineral intergrowths.
• * The
• cloudy zone
• in meteorites contains tetrataenite, a ferromagnetic mineral with potential as a sustainable magnet alternative.
• * Understanding tetrataenite's nanostructure is key to its magnetic applications.

Purpose of the Study:

• * To elucidate the 3D architecture of the meteorite cloudy zone at subnanometer resolution.
• * To model the mechanism of remanence acquisition during slow cooling.
• * To assess the paleomagnetic utility and potential for synthetic magnet development.

Main Methods:

• * High-resolution electron diffraction and tomography.
• * Atom probe tomography (APT).
• * Micromagnetic simulations.

Main Results:

• * Revealed isolated tetrataenite islands in an ordered superstructure matrix.
• * Identified clustering of three crystallographic variants influencing magnetic encoding.
• * Modeled remanence acquisition via magnetic domain state transformations driven by Fe-Ni ordering at 320 °C.
• * Determined that coarse and intermediate cloudy zones are suitable for paleomagnetism, while fine regions mimic rare-earth magnets.

Conclusions:

• * The cloudy zone records a coherent paleomagnetic snapshot at 320 °C.
• * Specific regions of the cloudy zone are valuable for paleomagnetic studies.
• * Fine-grained tetrataenite offers a pathway for developing synthetic permanent magnets.