Studies of the Verwey Transition in Magnetite
Z. Tarnawski, A. Wiecheć, M. Madej, D. Nowak, D. Owoc, G. Król, Z. Kąkol, L. Kolwicz-Chodak, A. KozŁowski and T. Dawid
Department of Solid State Physics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków, Poland
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Studies of the specific heat and simultaneous AC magnetic susceptibility (ρ') and electric resistance of stoichiometric magnetite single crystal are presented. The temperature hysteresis of the Verwey transition is of 0.03 K found from the specific heat data confirming its first-order character. The continuous temporal change of ρ' at TV can be switched off by an external magnetic field without affecting the transition. The electrical resistance decreases continuously with increasing temperature with a rapid change of slope at the point when the phase transition is completed. It was concluded that the magnetic degrees of freedom do not actively participate in the transition and that the entropy released at TV may come from ordering electrons.
DOI: 10.12693/APhysPolA.106.771
PACS numbers: 61.18.Bn, 75.40.-s, 71.20.Lp