Giant spontaneous resistivity jumps in La0.825Ce0.175Fe12B6

We report the observation of spontaneous and very sharp resistivity jumps at low temperatures in the antiferromagnetic itinerant-electron system La0.825Ce0.175Fe12B6. This intermetallic compound undergoes multiple magnetic transformations, antiferromagnetic–ferromagnetic (AFM–FM) and ferromagnetic–paramagnetic (FM–PM), triggered by changes in both the temperature and the applied magnetic field. The magnetoresistance isotherms display irreversible abrupt steps at T ≤ 4 K, whereas the field dependence of the resistivity becomes smooth above 4 K. Meanwhile, the evolution with time of the electrical resistivity exhibits a huge spontaneous jump after an incubation time when both the applied magnetic field and temperature are constant. A giant negative magnetoresistance (MR = −71%) is discovered associated with the magnetic-field-induced first-order AFM-FM transition.