Heat Capacity and Elastic Constants of Fe_3-xZn_xO₄in the Vicinity of the Verwey Transition

Abstract

The results of the heat capacity and elastic constant studies of Fe3-x Ζn x O 4 (x < 0.04) series are reported. Adiabatic heat capacity measurements, performed on single crystals, show the clear change of the transition character from first order for low Zn content (x < 0.012) to the higher order in 0.012 < x < 0.035 regime. The change of transition order is accompanied by the change in the heat capacity base lines below the Verwey transition temperature Tv. From the elastic constants measurements we found that cli, (Cl1 -c12) and c44 modes exhibit anomalies at Tv but only shear wave c44 show critical softening while approaching transition from high temperatures. This behavior can be linked to the results obtained by the heat capacity studies. These point to the important role of the lattice contribution to the mechanism of the Verwey transition.

Brillouin scattering studies inFe3O4across the Verwey transition

“…The effect of nonstoichiometry, either by oxygen deficiency or impurities has been studied recently [16][17][18][19][20][21][22]. Nonstoichiometry shifts the Verwey transition to lower temperatures as well as broadens the transition [16].…”