High Frictional Anisotropy of Periodic and Aperiodic Directions on a Quasicrystal Surface
Jeong Young Park,1
D. F. Ogletree,1
M. Salmeron,1*
R. A. Ribeiro,2
P. C. Canfield,2
C. J. Jenks,2
P. A. Thiel2
Strong friction anisotropy is found when the twofold surface of an atomically clean aluminum-nickel-cobalt quasicrystal slides against a thiol-passivated titanium-nitride tip. Friction along the aperiodic direction is one-eighth as much as that along the periodic direction. This anisotropy, which is about three times as large as the highest value observed in anisotropic crystalline surfaces, disappears after the surface is oxidized in air. These results reveal a strong connection between interface atomic structure and the mechanisms by which energy is dissipated, which likely include electronic or phononic contributions, or both.
1 Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA.
2 Ames Laboratory and Departments of Chemistry, Physics and Astronomy, and Materials Science and Engineering, Iowa State University, Ames, IA 50011, USA.
* To whom correspondence should be addressed. E-mail: mbsalmeron{at}lbl.gov
