  Introducing magnetism to the surface state of topological insulators, such as
Bi2Te3, can lead to a variety of interesting phenomena. We use scanning
tunneling microscopy (STM) to study a single quintuple layer (QL) of the van
der Waals magnet Fe3GeTe2 (FGT) that is grown on Bi2Te3 via molecular beam
epitaxy. STM topographic images show that the FGT grows as free-standing
islands on Bi2Te3 and outwards from Bi2Te3 steps. Atomic resolution imaging
shows atomic lattices of 390 +- 10 pm for FGT and 430 +- 10 pm for Bi2Te3,
consistent with the respective bulk crystals. A moir\'e pattern is observed on
FGT regions with a periodicity of 4.3 +- 0.4 nm that can be attributed solely
to this lattice mismatch and thus indicates zero rotational misalignments.
While most of the surface is covered by a single QL of the FGT, there are small
double QL regions, as well as regions with distinct chemical terminations due
to an incomplete QL. The most common partial QL surface termination is the FeGe
layer, in which the top two atomic layers are missing. This termination has a
distinctive electronic structure and a (sqrt3 x sqrt3)R30 reconstruction
overlaid on the moir\'e pattern in STM images. Magnetic circular dichroism
(MCD) measurements confirm these thin FGT films are ferromagnetic with TC ~190
K.
