Low temperature divergence in the AHE and AMR of ultra-thin Pt/Co/Pt trilayers

Abstract We study the anomalous Hall effect (AHE) and anisotropic magnetoresistance (AMR) in a series of ultra-thin Pt/Co(x)/Pt trilayers ( 0.1 nm ⩽ x ⩽ 0.5 nm ). We find that the AHE exhibits a significant increase at low temperatures (T). This increase cannot be attributed to a trivial increase in magnetization or resistivity. A similar T dependence is observed in the AMR measurements. Interestingly, these effects show almost no dependence on cobalt thickness. Our measurements indicate that the deviation from common behavior can be attributed to an induced magnetic proximity effect in the Pt layers that increases at low temperatures, in agreement with previous reports. An alternative explanation related to the evolution of a non-continuous magnetic layer is considered as well.