Viable scaling mechanism ensuing anomalous Hall effect in Si/Ni multilayers from 2 K-300 K

Abstract

A systematic study of the scaling mechanisms driving the anomalous Hall effect (AHE) in Si/Ni multilayers was conducted from 2 K to 300 K on ${[Si\left(40\AA \right)/Ni\left(t_{Ni}\AA \right)]}_{20}$​ multilayers. Structural analysis revealed polycrystalline Ni layers and amorphous Si layers. As $t_{Ni}$​ decreased, Ni nanocrystallite size reduced, while the surface-to-volume ratio and Si/Ni interface roughness increased. Multilayers with $t_{Ni}\ge 40\AA$ exhibited ferromagnetic behavior, while those with $t_{Ni}<40\AA$ were superparamagnetic. Decreasing $t_{Ni}$ also increased longitudinal resistivity due to enhanced interface roughness, higher surface-to-volume ratio, and increased tunneling between Ni nanocrystallites. AHE studies showed that Hall resistance peaked with decreasing $t_{Ni}$​ but declined for $t_{Ni}<40\AA$, due to superparamagnetism. Skew scattering dominated Hall resistance enhancement at all temperatures, but as the temperature increased from 2 K to 300 K, a transition from skew scattering to the side-jump mechanism was observed.