  Magnetic exchange driven proximity effect at a magnetic insulator /
topological insulator (MI/TI) interface provides a rich playground for novel
phenomena as well as a way to realize low energy dissipation quantum devices.
Here we report a dramatic enhancement of proximity exchange coupling in the MI
/ magnetic-TI EuS / Sb$_{2-x}$V$_x$Te$_3$ hybrid heterostructure, where V
doping is used to drive the TI (Sb$_{2}$Te$_3$) magnetic. We observe an
artificial antiferromagnetic-like structure near the MI/TI interface, which may
account for the enhanced proximity coupling. The interplay between the
proximity effect and doping provides insights into controllable engineering of
magnetic order using a hybrid heterostructure.
