Evidence for a single-stage Verwey-transition in perfect magnetite

Abstract

Recently, two specific heat peaks occurring near the Verwey transition (T_v = 125 K) in nominally stoichiometric powdered magnetite (Fe₃O₄) have been interpreted as representing characteristic intrinsic phenomena in stoichiometric Fe₃O₄. Magnetic after-effect (MAE) measurements performed on this same material suggest, however, that the lower peak (113 K) originates from lattice defects which have been produced during preparation of the powder from the initial bulk single crystal. Our MAE investigations on perfect Fe₃O₄ crystals support the single-stage character of the Verwey transition at 125 K.