Signal transfer in a chain of stray-field coupled ferromagnetic squares

We study the vortex-core dynamics in a chain of three stray-field coupled permalloy squares. Time-resolved scanning transmission x-ray microscopy is employed to image the out-of-plane magnetization of the cores. After exciting the first element via a short in-plane magnetic field pulse, the excitation can be transferred through the chain via dipolar interaction. The transfer efficiency of the gyrotropic vortex motion strongly depends on the configuration of the core polarizations. For alternating polarizations, a transfer efficiency of about 56% to the third square is achieved. The chain can be switched back and forth between the transmitting and a locking state.