Spin-transfer nano-oscillators (STNO) can generate a microwave voltage output based on a DC input current. However, a single oscillator generates a relatively small amount of power. To address this issue, a solution is to have an array of STNOs and synchronize them, thus leading to much greater generated power. Achieving synchronization in a large array of oscillators can be challenging due to the complexity of interactions. Here, we proposed a structure that can allow synchronization in a large array of STNO by means of spin waves in a thin magnetic film. The structure is based on a honeycomb configuration, which has low-damping hexagonal regions with high-damping embedded triangle regions (Fig. 1). STNOs are placed at each narrow neck of the pattern. The spin waves generated by the STNO propagate within the low-damping region, whereas they are damped in the high-damping regions. The narrow neck width is smaller than the spin wave wavelength, so that the spin waves do not pass there. Thus, each STNO only has nearest-neighbor interactions (Fig. 2). By limiting the range of interaction, synchronization in a large array of STNOs is possible. Furthermore, the coupled oscillations can be tuned by either changing the STNO driving current or using extra current on the high damping region to reduce the effective damping constant to allow more connections among adjacent STNOs within a certain region.

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