Quantitative electron diffraction evidence for one-dimensional ordering in magnetite above the Verwey transition

Abstract

Energy-filtered electron diffraction and three-dimensional reciprocal lattice mapping was used to study the nature of diffuse scattering in magnetite above the Verwey transition temperature. Characteristic Huang scattering associated with a single molecular polaron is observed at room temperature. As the temperature is lowered, the experiment shows narrowing of diffuse scattering in the (001) directions and additional ringlike diffuse scattering at q approximately 0.8, which suggests the presence of one-dimensional structures above the Verwey transition. Experimental measurements of temperature-dependent correlation lengths and diffuse scattering intensity indicate an increase in the number and length of the one-dimensional structure as the temperature is cooled toward the transition. This study demonstrates the electron sensitivity to atomic displacement and the quality of electron diffraction data for studying phase transition in complex materials.