Direct observation of ferrimagnetic/ferroelastic domain interactions in magnetite below the Verwey transition
Abstract 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.
We present an electronic structure calculation of the valence band for some II--VI binary/ternary alloy interfaces. We use the empirical tight-binding method and the surface Green's function matching method. For the ternary alloys we use our previously set Hamiltonians they describe well the band gap change with composition obtained experimentally. At the interface domain, we find three non-dispersive and two interface states besides the known bulk bands. The non-dispersive states are reminiscent of the ones already obtained experimentally as well as theoretically, in (001)-oriented surfaces. We make use of the available theoretical calculations for the (001)-oriented surfaces of the binary compounds and for the binary/binary interfaces to compare our new results with.