Self-hybridization of magnons in synthetic antiferromagnetic multilayers*

Antiferromagnets possess many potential applications due to their high-frequency dynamic properties. Here, we study combinations of ferromagnetic layers separated by non-magnetic layers of suitable thicknesses. These structures have an antiferromagnetic coupling between adjacent ferromagnetic layers and are called synthetic antiferromagnets. Synthetic antiferromagnets are useful materials for tuning magnon frequencies by manipulating magnon-magnon interactions. In this work, we consider Permalloy-Ru tetralayer structures. We previously predicted that tetralayers contain self-hybridization effect amongst acoustic or optical magnon pairs. We have now experimentally observed self-hybridization effects that are in close agreement with both macrospin model calculations and micromagnetic simulations. This work paves the way for electric tunability of magnon-magnon interactions.