Enhancement in anomalous Hall resistivity of Co/Pd multilayer and CoPd alloy by Ga+ ion irradiation

In this paper, we report the effect of Ga + ion irradiation on anomalous Hall effect (AHE) and longitudinal resistivity (ρxx )i n (Co(3˚ ˚80 multilayer and Co42Pd58 alloy. 4- and 2-fold increases in anomalous Hall resistivity (ρAH) in the Co/Pd multilayer and CoPd alloy have been observed after irradiations at doses of 2.4 × 10 15 and 3.3 × 10 15 ions/cm 2 ,r espec- tively. Skew scattering and side jump contributions to AHE have been analyzed based on the scaling relationship ρAH = aρxx + bρ 2. For the Co/Pd multilayer, AHE is mainly affected by ion irradiation-induced interface diffusion and defects. For the CoPd alloy, the increase in doses above 1.5 × 10 15 ions/cm 2 induces a sign change in skew scattering, followed by the skew scatter- ing contribution to AHE overwhelming the side jump contribution, this phenomenon should be attributed to irradiation-induced defects and modifications in chemical ordering. Copyright c EPLA, 2014