The Role of Grain Boundaries in Determining the Transport Properties in Magnetite

Abstract

We present magnetoresistance and Hall-effect measurements on single crystal magnetite (Fe3O4) close to the Verwey transition TV = 123.8 K. We show that the formation of grain boundaries accompanying the reduction in crystal symmetry plays a significant role in the electron scattering mechanism, and that grain boundaries can account for the apparent change in sign of the charge carriers below TV.