  Polarons are entities of excess electrons dressed with local response of
lattices, whose atomic-scale characterization is essential for understanding
the many body physics arising from the electron-lattice entanglement, but yet
difficult to achieve. Here, using scanning tunneling microscopy and
spectroscopy (STM/STS), we show the visualization and manipulation of single
polarons with different origin, i.e., electronic and conventional polarons, in
monolayer CoCl2, that are grown on HOPG substrate via molecular beam epitaxy.
Four types of polarons are identified, all inducing upward local band bending,
but exhibiting distinct appearances, lattice occupations, polaronic states and
local lattice distortions. First principles calculations unveil three types of
polarons are stabilized by electron-electron interaction. The type-4 polaron,
however, are driven by conventional lattice distortions. All the four types of
polarons can be created, moved, erased, and moreover interconverted
individually by the STM tip, allowing precise control of single polarons
unprecedently. This finding identifies the rich category of polarons and their
feasibility of manipulation in CoCl2, which can be generalized to other
transition metal halides.
