Energy Transfer between Coupled Planar Magnon Waveguides Near an Exceptional Point

Energy transfer is investigated in coupled planar magnon “ferromagnet–normal metal” heterostructures with equivalent amplification and damping of spin waves, in which an exceptional point (point in the space of the parameters of a system where its eigenvalues and eigenvectors degenerate) can be observed. It is shown that an increase in the direct current of different polarities (causing a change in the spin-polarized current) leads to an increase in the length of energy transfer from one heterostructure to another, which tends to infinity at the exceptional point. The mismatch in the natural magnetization damping constants of the two waveguides reduces the critical current at which the exceptional point arises, whereas the mismatch in the wavenumbers (the absence of phase-velocity synchronism) increases the critical current at a bounded energy transfer length. The results presented can be used to design controlled magnon directional interconnects.