Tunable Topological States and Chirality by Non-Equilibrium Antimagnons in Magnetic Multilayers

Abstract: Realizing novel topological states in magnonics systems opens new opportunities for developing robust low-power spin-wave-based devices. Introducing non-equilibrium antimagnon can bring additional effects to the topology and chirality. In this report, we revisit the ferromagnetic multilayers with a non-equilibrium state and generalize it to antiferromagnetic/ferromagnetic multilayers. We found that non-equilibrium states with the perturbative coupling of magnon and antimagnon can turn an originally trivial state into a non-trivial one, characterized by Chern number. Both coherent coupling and dissipative coupling are found in the band structures and can be controlled by the external magnetic field and torques. Further, in the bilayer unit cell, all four possible chirality combinations are achieved at a few GHz. Our work presents an accessible platform for realizing topological magnonic surface states, paving the way for controlling magnon chirality and facilitating various types of coupling.