High-field transport properties of itinerant electron metamagnetic Co(S1-Se )2

The Co(S1-xSex)2 compounds are known to exhibit itinerant electron metamagnetism (IEM). We present field dependence of electrical resistivity and Hall effect of the compounds with 0 ≤ x < 0.15. It was found that the magnetoresistance shows a positive jump associated with the IEM. This jump is nearly independent of temperature. We also observed a jump in the field dependence of Hall resistivity, which is attributable to the anomalous Hall effect due to the onset of ferromagnetism. Our analyses revealed that the ordinary Hall coefficient decreases considerably by the IEM. These results are discussed in terms of the proposed electronic structure of CoS2, in which a highly spin polarized state is achieved.