Edge-enhanced negative magnetoresistance in a WSe2/Fe3GeTe2 heterostructure

Dzyaloshinskii-Moriya interaction (DMI), the antisymmetric exchange interaction in noncentrosymmetric magnets, is a key ingredient in forming and manipulating the magnetic skyrmion, a promising candidate for next-generation data storage. With the development of non-Hermitian topological phases, the role of DMI has been extended to a broader stage recently. The non-Hermitian skin effect (NHSE) of magnons has been theoretically predicted to take place in magnetic systems with DMI and dissipation. Though exceptional band structures in van der Waals (vdW) magnetic structures have been observed, the NHSE of magnons has not been identified yet. Here we fabricate $\mathrm{W}{\mathrm{Se}}_{2}/\mathrm{F}{\mathrm{e}}_{3}\mathrm{Ge}{\mathrm{Te}}_{2}$ vdW heterostructure and observe the edge-enhanced negative magnetoresistance (NMR). The larger NMR at the sample's edges is attributed to the stronger electron-magnon scattering at the boundaries, indicating the edge accumulation of magnons. The aggregation of magnons towards sample boundaries is consistent with the magnonic NHSE, which is favored by the interface DMI and magnetic dissipation inherently in the heterojunction. Our work should be valuable for understanding the non-Hermitian topology in magnetic systems.