  Magnetic proximity effect of a topological insulator in contact with a
ferromagnet is reported in thin film bilayers of 15 nm thick $BiSbTe_3$ on
either 15 or 40 nm thick $SrRuO_3$ on (100) $SrTiO_3$ wafers. Magneto transport
results of the bilayers were compared with those of reference films of 15 nm
$BiSbTe_3$ and 15 or 40 nm $SrRuO_3$. Comparison of the temperature coefficient
of resistance [(1/R)$\times$dR/dT which is qualitatively proportional to the
magnetization] of the bilayer and reference ferromagnetic film normalized above
$T_c$, shows a clear suppression in the bilayer by about 50% just below $T_c$,
indicating a weaker proximity magnetization in the bilayer. Resistance
hysteresis loops versus field at 1.85$\pm$0.05 K in the bilayer and reference
films show a clear magnetic proximity effect, where the peak resistance of the
bilayer at the coercive field shifts to lower fields by $\sim$30% compared to a
hypothetical bilayer of two resistors connected in parallel with no interaction
between the layers. Narrowing of the coercive peaks of the bilayers as compared
to those of the reference ferromagnetic films by 25-35% was also observed,
which represents another signature of the magnetic proximity effect.
