The Ohio University atomic logo is written on a Ag(111) surface at 6 K temperature [1].

(51 silver atoms, 42 nm x 26 nm area, image courtesy: Saw-Wai Hla)

[1] S.-W. Hla, “STM Single Atom/Molecule Manipulation and Its Application to Nanoscience and Technology ”, J. Vac. Sci. Technol. B 23 (2005) 1351-1360. [invited article].