  We study nonequilibrium roughening during compressive plastic flow of
initially flat Cu$_{50}$Zr$_{50}$ metallic glass using large-scale molecular
dynamics simulations. Roughness emerges at atomically flat interfaces beyond
the yield point of the glass. A self-affine rough topography is imprinted at
yield and is reinforced during subsequent deformation. The imprinted
topographies have Hurst exponents that decrease with increasing strain-rate and
temperature. After yield, the root-mean-square roughness amplitude grows as the
square-root of the applied strain with a prefactor that also drops with
increasing strain-rate and temperature. Our calculations reveal the emergence
of spatial power-law correlations from homogeneous samples during plastic flow
with exponents that depend on the rate of deformation and the temperature. The
results have implications for interpreting and engineering roughness profiles.
