Direct observation of ferrimagnetic/ferroelastic domain interactions in magnetite below the Verwey transition

The magnetic behaviour of magnetite at low temperatures is dominated by its transformation to a monoclinic crystal structure that is simultaneously ferrimagnetic, ferroelastic and ferroelectric below ∼ 125 K (the Verwey transition). Here we use electron microscopy to reveal the relationship between ferrimagnetic and ferroelastic domain structures in monoclinic magnetite. We present dynamic observations of magnetite during heating and cooling across the Verwey transition, revealing a diversity of unexpected interaction phenomena between crystallographic twins and magnetic domain walls. This study provides a new understanding of the low-temperature magnetic properties of magnetite that will affect a broad range of rock magnetic studies, from the interpretation of magnetic remanence in terrestrial rocks and sediments to the search for biogenic magnetite in extraterrestrial materials.