  Single-ion lanthanide-organic complexes can provide stable magnetic moments
with well-defined orientation for spintronic applications on the atomic level.
Here, we show by a combined experimental approach of scanning tunneling
microscopy and X-ray absorption spectroscopy that
dysprosium-tris(1,1,1-trifluoro-4-(2-thienyl)-2,4butanedionate) (Dy(tta)$_3$)
complexes deposited on a Au(111) surface undergo a molecular distortion,
resulting in distinct crystal field symmetry imposed on the Dy ion. This leads
to an easy-axis magnetization direction in the ligand plane. Furthermore, we
show that tunneling electrons hardly couple to the spin excitations, which we
ascribe to the shielded nature of the $4f$ electrons.
