Impurity effects upon the Verwey transition in magnetite

Abstract

Magnetite single crystals Fe 3Ϫx M x O 4 doped with M ϭNi, Co, Mg, Al, Ga, and Ti were grown and annealed under a controlled atmosphere to produce homogeneous and oxygen stoichiometric samples. The cation vacancy concentration of the samples was proved to be lower than 10 Ϫ6 by means of magnetic disaccommodation spectroscopy. The Verwey temperature shift as function of the substituent concentration was determined from the temperature dependence of the resistivity. The systematics of the transition temperature shift as function of the concentration and nature of the substituents is indicative that the mechanism of the transition is related to the second-neighbor Coulomb interaction of the cations on the octahedral sites.

Swift heavy ion irradiation-induced modifications in structural, magnetic and electrical transport properties of epitaxial magnetite thin films

“…At a critical value of the ratio R c = U / W Ϸ 2.2 ͑where U is interionic Coulomb potential and W is bandwidth͒, the Verwey transition will disappear. This model has been proved and fully in agreement with various experimental situations such as impurity substitution, 27 pressure effect 28 on Verwey transition, the deviation from the ideal stochiometery 29 and Verwey transition in lowdimensional systems. 5 All these experiments proposed the variation of bandwidth and interionic Coulomb interaction and its effect on Verwey transition temperature.…”

Heat Capacity and Elastic Constants of Fe3-xZnxO4in the Vicinity of the Verwey Transition

“…The strongest effect on Tv is caused by nonstoichiometry and Zn or Ti doping [1][2][3][4]. Despite the fact that all three kinds of defects introduce different perturbations to the system the properties of Fe3(ι-δ)O4 , Fe3-x ΤiO4 and Fe3 -x Ζn O 4 are very similar, which can be seen from the universal linear TV vs. 3δ = x dependence.…”

Seeded growth of ferrite nanoparticles from Mn oxides: observation of anomalies in magnetic transitions

“…Impurities include metal ions such as Al, 10 Mn, 11 and Zn. 12 Not only impurities, small cationic vacancy can also make the transition lower or disappear, such as Fe 3−δ O 4 with δ = 0.066.…”