Observation of the anomalous Hall effect in proximity coupled Cr2Ge2Te6/graphene heterostructures

Introducing magnetism into graphene is expected to exhibit unique transport phenomena. However, how to properly introduce magnetism into graphene has remained a major challenge. Here we report a method to induce spin polarization in graphene by the proximity effect. The anomalous Hall effect is clearly observed in heterostructures of Cr₂Ge₂Te₆ (CGT)/graphene. The temperature dependence of the anomalous Hall resistance coincides with that of the magnetization of the bulk CGT. Moreover, control experiments exclude the possibility of a Lorentz force-induced nonlinear Hall signal either from the coexistence of two types of carriers in graphene or from the stray magnetic field of the CGT substrate. All of our experimental results strongly suggest that the observed anomalous Hall resistance is caused by the spin polarization in graphene induced by the magnetic proximity effect. Density functional theory calculations indicate that the spin density of the CGT would spread into the adjacent graphene and induce the spin polarization of the carriers in graphene. Our results provide an efficient and reliable way to achieve spin polarization in graphene and shed light on the development of graphene spintronic devices.