Surface Structural Transitions on the Icosahedral Quasicrystal ${\mathrm{Al}}_{70}{\mathrm{Pd}}_{20}{\mathrm{Mn}}_{10}$

We report the observation in real space of a structural transition on the surface of the quasicrystal ${\mathrm{Al}}_{70}{\mathrm{Pd}}_{20}{\mathrm{Mn}}_{10}$ from icosahedral to body-centered cubic caused by bombardment with 1.5-keV ${\mathrm{Ar}}^{+}$ ions. Subsequent annealing at 700 K restores the quasicrystalline structure of the surface. In addition to illustrating the sensitivity of the surface structure to local stoichiometry and demonstrating the thermodynamic stability of the quasicrystalline state, our observations open the way to investigating the assembly kinetics on quasicrystalline surfaces.