LAUSR

We study magnon transmission in the sandwich structure of ferromagnetic insulators (FMIs), antiferromagnetic insulators (AFMI), and ferromagnetic insulators (FMI) by atomistic spin-model simulations. Magnon junction effects (MJEs), which have been reported in magnon junction (MJ) experiments, can be reproduced in this work, demonstrating the importance of spin-dependent magnon blocking effects (MBEs) in a MJ structure. Moreover, AFMI spacers with various structures are investigated. We show that the MJE is sensitive to the characteristics of the AFMI spacer such as orientation of N\'eel vector, types of AFMI spin configuration, and intrinsic exchange interaction. It is found that these phenomena are rooted in the magnon selection rules between two FMIs of different magnonic polarization. Based on the mechanism studied above, we further propose an in-plane MJE and give a feasible experimental prediction using nonlocal magnon-mediated current-drag measurement. Our work provides insight into magnon transmission in MJ and serves as a promising tool for future magnon circuits.