Magnetoresistance extremum at the first-order Verwey transition in magnetite)

A large negative magnetoresistance (MR) sharply peaked at the first-order Verwey transition temperature (Formula presented) K has been measured in a synthetic single crystal of magnetite (Formula presented), (Formula presented). At (Formula presented) T the MR extremum exhibited a peak value of -17% and a full width at half maximum of 0.53±0.08 K. At the lower and higher ends of the measurement interval 114-126 K encompassing (Formula presented), negative MR values of 3% and 0.5%, respectively, were obtained at 7.7 T. In applied magnetic fields up to 7.7 T the field-dependent discontinuous entropy change at (Formula presented), (Formula presented), decreases linearly with respect to the zero-field value (Formula presented), according to (Formula presented). At (Formula presented), the associated discontinuous change of the average magnetic moment (Formula presented) obtained from the MR data was of the order of (Formula presented) of (Formula presented). This is concordant with the corresponding value obtained in previous magnetization studies.