Magnon mode transition in synthetic antiferromagnets induced by perpendicular magnetic anisotropy

In this work, we numerically studied the static and dynamic properties of synthetic antiferromagnets (SAFs) with perpendicular magnetic anisotropy (PMA). The observed high/low frequency magnon is either optical/acoustic or left/right-hand mode depending on the strength of PMA, i.e., a PMA-induced magnon mode transition. For weaker PMA, the ground magnetization state of the SAFs is in-plane magnetized exhibiting the optical/acoustic magnon mode with high/low frequency. While for stronger PMA, the ground magnetization state of the SAFs is perpendicularly magnetized and characterized by the presence of the left- and right-hand magnon modes. Furthermore, by tilting the external field toward the SAF film plane, hybridization between the acoustic and the optical magnon modes can be realized and approaches a strong coupling regime by modulating the strength of PMA and the magnitude of interlayer exchange coupling. Our findings provide new insight into the magnetization dynamics in synthetic antiferromagnets with perpendicular magnetic anisotropy for quantum magnonics.