Specific heat and magnetization studies of Fe_3−xCo_xO₄ and Fe_3−yO₄ single crystals in the neighbourhood of the Verwey transition

Abstract

To test our previous conclusions about the appearance of two separate peaks in the neighbourhood of the Verwey transition in single-crystal magnetite, we have measured the specific heat and magnetization around the Verwey transition of Fe_3-x Co_xO₄, and Fe_3-yO₄ single crystals. Our present results confirm our previous conclusions: for Fe_3-xCo₄O₄ with 0 ≤ X ≤ 0·04, two transitions appear in the vicinity of the Verwey transition, and, for Fe_3-yO₄ with y ≥ 0·037 no transition is observed. The driving forces for the two anomalies are not connected.