Heat Capacity and Elastic Constants of Fe3-xZnxO4 in the Vicinity of the Verwey Transition
A. Kozłowskia, Z. Kąkola, H. Schwenkb, S. Bareiterb, C. Hinkelb, B. Luthib and J.M. Honigc
a Dept. of Solid State Physics, Faculty of Physics and Nuclear Techniques, University of Mining and Metallurgy, Mickiewicza 30, 30-059 Kraków, Poland
b Physikalisches Institut der Universität Frankfurt am Main, Germany
c Dept. of Chemistry, Purdue University, West Lafayette, IN, USA
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The results of the heat capacity and elastic constant studies of Fe3-xZnxO4 (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 c11, (c11-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.
DOI: 10.12693/APhysPolA.97.883
PACS numbers: 62.20.Dc, 63.20.-e, 64.60.-i, 65.40.+g