Measurements of interlayer exchange coupling of Pt in Py|Pt|Py system

Abstract

Ferromagnetic coupling strength through Pt is experimentally determined using ferromagnetic resonance studies of Py|Pt(dPt)|[Py|Fe] for Pt thicknesses, dPt, between 0.5 and 2.2 nm. The coupling strength decreases exponentially with the Pt thickness from 4.5 mJ/m2 for dPt = 0.5 nm and reduced to less than 0.02 mJ/m2 for dPt = 2.2 nm. The mechanism mediating exchange coupling is assumed to originate from the induced magnetization of Pt due to its proximity to ferromagnetic Py. The fitting thickness dependence of coupling with this model yields a characteristic coupling length scale of ξ = 0.31 ± 0.01 nm. Additionally, the molar susceptibility of proximity induced Pt is found to be 1.4 × 10−7 ± 0.2 × 10−7 m3/mol, an enhancement of ∼100 times as compared to bulk Pt. Ruderman-Kittel-Kasuya-Yosida type oscillations with a period of ∼0.8 nm are also observed as a small contribution of the total coupling.