  We report here on time-resolved x-ray diffraction measurements following
femtosecond laser excitation in pure bulk chromium. Comparing the evolution of
incommensurate charge-density-wave (CDW) and atomic lattice reflections, we
show that, few nanoseconds after laser excitation, the CDW undergoes different
structural changes than the atomic lattice. We give evidence for a transient
CDW shear strain that breaks the lattice point symmetry. This strain is
characteristic of sliding CDWs, as observed in other incommensurate CDW
systems, suggesting the laser-induced CDW sliding capability in 3D systems.
This first evidence opens perspectives for unconventional laser-assisted
transport of correlated charges.
