Large spontaneous Hall angle in [Co, CoFe/Pt] multilayer

Abstract

We have quantitatively investigated the Hall effect in [Co, CoFe/Pt] multilayer films. The [Co, CoFe/Pt] multilayers exhibit large spontaneous Hall resistivity ( ρ H) and Hall angle ( ρ H/ ρ). Even though the Hall resistivity in [Co, CoFe/Pt] multilayer films (2.7–4 × 10 −7 Ω cm) is smaller than that of amorphous RE–TM alloy films which show large spontaneous Hall resistivity (<2 × 10 −6 Ω cm), the Hall angle of multilayer (6–8%) is almost twice than that in amorphous rare earth–transition metal alloy films (∼3%). The Hall angle provides evidence of the effects of the exchange interaction of the Hall scattering. The exchange is between conduction electron spins and the localized spins of the transition metal. The large Hall angle of [Co, CoFe/Pt] multilayer can be considered due to the high spin polarization and high Curie temperature of Co and CoFe transition metal layers. Even though the role of interfaces and surfaces in the magnetic properties of multilayer films may dominate that of the bulk, the Hall effects in [Co, CoFe/Pt] multilayer may be mainly dominated by the bulk effect.