The influence of exchange-bias on the resonance frequencies and damping in IrMn3/[Co/Pt] multilayers

In order to realise single on-chip three axis magnetic field sensing technology without the need for convoluted die stacking, perpendicular media must be exploited. This poses additional challenges in both static-bias and the dynamics of the stack. Presented here are ferromagnetic resonance measurements (FMR) on exchange-biased multilayers of IrMn 3 /[Co/Pt] n . We chart the evolution of the different anisotropies caused by both magnetic field annealing and increasing repetition number n . The damping of these stacks does not obey the usual symmetry seen in single and bilayer samples with in-plane anisotropy, but instead follows a sin 2 ( θ ) dependence. This, we propose, is entirely dominated by spin diffusion from the Co layers into the adjacent heavy metal layers. This is modelled using a simple effective circuit model, providing a guide for the optimisation of complex multilayers. • The evolution of anisotropy in [Co/Pt] multilayers was investigated using FMR. • The damping was dominated by spin-current sinking in adjacent heavy metal layers. • An effective circuit model was proposed to model the parallel damping contributions.