A fundamental morphological instability of mobile dislocations in crystals and related line defects was identified. A positive gradient of the local driving force along the direction of defect motion destabilized long-wavelength vibrational modes and produced a so-called fingering pattern. The minimum unstable wavelength scaled as the inverse square root of the force gradient. The onset of the instability was demonstrated by simulations of a screw dislocation in Al (via molecular dynamics) and of a vortex in a 3-dimensional XY rotator model.

Fingering Instability of Dislocations and Related Line Defects. M.Li, B.B.Smith, R.L.B.Selinger: Physical Review Letters, 1999, 82[11], 2306-9