  Quantitative density measurements from electron scattering show that shear
bands in deformed Al_{88}Y_{7}Fe_{5} metallic glass exhibit alternating high
and low density regions, ranging from -9 % to +6 % relative to the un-deformed
matrix. Small deections of the shear band from the main propagation direction
coincide with switches in density from higher to lower than the matrix and vice
versa, indicating that faster and slower motion (stick-slip) occurs during the
propagation. Nano-beam diffraction analyses provides clear evidence that the
density changes are accompanied by structural changes suggesting that shear
alters the packing of tightly-bound short- or medium-range atomic clusters.
This bears a striking resemblance to the packing behavior in granular shear
bands formed upon deformation of granular media.
