ANISOTROPY SLIDING FRICTION ON THE TRIGLYCINE SULFATE (010)SURFACE

The frictional properties of freshly cleaved (010) surfaces of the fer roelectric TriGlycine Sulfate (TGS) were investigated by combined scan ning and friction force microscopy under ambient conditions. A frictio nal contrast could be observed between domains with different electric al polarity, as well as between terraces inside individual domains whi ch are separated by steps of half of the unit-cell height or an odd mu ltiple of this value. The latter contrast mechanism originates from th e arrangement of the molecules at the surface which is chemically homo geneous, but structurally rotated by 180 degrees between different ter races. The resulting asymmetric surface potential gives rise to a fric tional anisotropy in different directions that can be detected by the force microscope, as well as to a change of the frictional force betwe en forward and backward scan direction.