Extraordinary Hall effect in CoxPt100−x films

CoxPt100−x alloy films, 8.7⩽x⩽40.6, have been fabricated by the magnetron co-sputtering technique. The structure of the films has been studied by x-ray diffraction and transmission electron microscopy. The results indicate the existence of CoPt3 phase in these films. Electric transport and magnetotransport measurements have been performed in the temperature range of 5–300 K and field range of −5–5 T, in which the longitudinal resistivity (ρxx) and extraordinary Hall resistivity (ρs) have been obtained. A power law dependence of extraordinary Hall resistivity on the longitudinal resistivity, ρs∝ρxxv, is observed, however the value of the exponent (v) changes from 1 to 1.6 as the temperature changes from 5 to 100 K and above. Different v values suggest different mechanisms of the extraordinary Hall effect. The dependence of the Hall resistivity on the Co concentration, x, has also been studied.