  Van der Waals (vdW) heterostructures have attracted great interest because of
their rich material combinations.The discovery of two-dimensional magnets has
provided a new platform for magnetic vdW heterointerfaces; however, research on
magnetic vdW heterointerfaces has been limited to those with ferromagnetic
surfaces. Here we report a magnetic vdW heterointerface using layered
intralayer-antiferromagnetic MPSe3 (M=Mn, Fe) and monolayer transition metal
dichalcogenides (TMDs). We found an anomalous upshift of the excitonic peak in
monolayer TMDs below the antiferromagnetic transition temperature in the MPSe3,
capturing a signature of the interlayer exciton-magnon coupling. This is a
concept extended from single materials to heterointerfaces. Moreover, this
coupling strongly depends on the in-plane magnetic structure and stacking
direction, showing its sensitivity to their magnetic interfaces. Our finding
offers an opportunity to investigate interactions between elementary
excitations in different materials across interfaces and to search for new
functions of magnetic vdW heterointerfaces.
