Below the Verwey transition temperature (~110K in this experiment), Magnetite Fe3O4 structure distorts into a monoclinic shape, where one of the angles slightly deviates from 90° (β ≈ 90.23°). This distortion introduces a shear strain.
The change is accompanied by charge ordering of the Fe2+ and Fe3+ ions to form “trimerons”, valence-ordered Fe3+-Fe2+-Fe3+ linear structures, which confine the electrons and lead to an insulating behavior at low temperatures.
The transition involves both electronic localization and a significant lattice distortion, evidenced by a change in symmetry and unit cell dimensions.
Below the Verwey transition, the strain distribution becomes increasingly fragmented, which indicates localized stress concentrations due to internal layered phase variations. Here higher temperatures allow for stress relaxation, while lower temperatures promote strain localization.
Bragg Coherent X-ray Diffraction Imaging method was used here.
Source:
https://arxiv.org/html/2503.10417v1
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