Effect of in situ low-temperature annealing on anomalous Hall effect in Co nanocluster-assembled granular film

The Co nanocluster-assembled film was prepared by using a plasma-gas-condensation method. Subsequently, the sample was in-situ annealed in a vacuum at relatively low temperature. The effect of annealing temperature on electrical transport behaviors of Co nanocluster-assembled granular film were systematically investigated by a Physical Property Measurement System (PPMS). By this method, we successfully realized that the surface and interface of the Co cluster were slightly transformed but the cluster size was almost a constant. We discovered that the potential barrier at the interface between adjacent Co clusters decreased with increasing annealing temperature due to the decrease in the degree of atomic disorder at interface and surface. Meanwhile, the residual resistivity and saturated anomalous Hall resistivity increased monotonously as the annealing temperature increased. Furthermore, the scaling relation between anomalous Hall conductivity and residual longitudinal conductivity at 5 K was studied. The scaling relation agreed well with the universal character of the 1.6 scaling relation in the bad metal regime. This method provided a simple and effective way to study the effect of the microstructural transformation on electrical transport behavior in the granular film. Additionally, our results would provide an experimental basis for shining light on understanding of how the surface and interfacial scattering affected the AHE in magnetic granular film. [Display omitted] •Surface and interface of Co cluster was slightly adjusted by in-situ annealing.•The ρxx and ρxyA were effectively adjusted by the surface and interface transformation.•The scaling relation of σxyA∝σxx01.6 was obtained at 5 K.