HEAT-CAPACITY ANOMALIES AT THE VERWEY TRANSITION OF FE-3(1-DELTA)O-4

It is known that the order of the Verwey transition changes from first to second, and then to a higher order, as the value of delta increase s in magnetite, Fe-3(1-delta)O-4. The associated heat capacity anomaly changes its shape and size, and it eventually becomes a broad hump, i .e. a higher order transition. An attempt was made, with some success, at recovering the observed changes in heat capacity anomaly in terms of the two-state approximation, a generalized extension of the Strassl er-Kittel treatment. By changing the adjustable parameters as a smooth linear function of delta, a qualitative trend of the observed changes in heat capacity anomaly was reproduced.