Determination of surface stress anisotropy from domain wall fluctuations

The thermally induced meandering of domain walls between (2x1) and c(4x2) r egions on Ge(001) is analyzed with a scanning tunneling microscope in order to extract the anisotropy of the surface stress tensor. On small length sc ales the domain walls exhibit random walker behavior, whereas on larger len gth scales (>100 Angstrom) due to domain-wall repulsion originating from th e anisotropy in the surface stress tensor a deviation from this one-dimensi onal random-walk behavior is observed. We have determined a value of 0.13 /- 0.04 eV/(1 x 1) cell for the stress anisotropy. [S0163-1829(99)92411-X].