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

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(40Å)/Ni(t<inf>Ni</inf>Å)]<inf>20</inf>​ multilayers. Structural analysis revealed polycrystalline Ni layers and amorphous Si layers. As t<inf>Ni</inf>​ decreased, Ni nanocrystallite size reduced, while the surface-to-volume ratio and Si/Ni interface roughness increased. Multilayers with t<inf>Ni</inf>≥40Å exhibited ferromagnetic behavior, while those with t<inf>Ni</inf><40Å were superparamagnetic. Decreasing t<inf>Ni</inf> 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<inf>Ni</inf>​ but declined for t<inf>Ni</inf><40Å, 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.