Particle response during the yielding transition of colloidal glasses
  Yielding is central to the relaxation, flow and fracture of a wide range of soft and molecular glasses, but its microscopic origin remains unclear. Here, we elucidate the yielding of a colloidal glass by using x-ray scattering to monitor the structure factor during the yielding process. We apply a recently introduced combination of small-angle x-ray scattering and rheology to the oscillatory shear, and follow the structure factor during the increasing strain amplitude. Surprisingly, we observe a sharp transition in the orientational ordering of the nearest-neighbor structure upon yielding, in contrast to the smooth variation of the viscoelastic moduli. This transition is accompanied by a sudden change of intensity fluctuations towards Gaussian distributions. We thus identify yielding as a new, dynamically induced transition of the glass in response to the applied shear. 
D. V. Denisov, M. T. Dang, B. Struth, G. H. Wegdam, P. Schall
cond-mat.soft