  We investigate the nonlinear rheological behavior of colloidal suspensions of
Laponite, a synthetic clay, driven by a steady and homogeneous shear strain. We
show that the external drive leads to a drastic slowing down of the aging
dynamics or even, in some cases, in the rejuvenation of the system. Under
shear, after a surprisingly long time, the spontaneous aging process observed
at rest is suppressed. The system then reaches a non-equilibrium stationary
state, characterised by a complex viscosity depending on the applied shear
rate. In addition, the glass exhibits a non-Newtonian shear-thinning behavior.
These rheological behaviors confirm recent numerical and theoretical
predictions.
