  Plastic deformation of metallic glasses performed well below the glass
transition temperature leads to the formation of shear bands as a result of
shear localization. It is believed that shear banding originates from
individual stress concentrators having quadrupolar symmetry. To elucidate the
underlying mechanisms of shear band formation, microstructural investigations
were carried out on sheared zones using transmission electron microscopy. Here
we show evidence of a characteristic signature present in shear bands
manifested in the form of sinusoidal density variations. We present an
analytical solution for the observed post-deformation state derived from
continuum mechanics using an alignment of quadrupolar stress field
perturbations for the plastic events. Since we observe qualitatively similar
features for three different types of metallic glasses that span the entire
range of characteristic properties of metallic glasses, we conclude that the
reported deformation behavior is generic for all metallic glasses, and thus has
far-reaching consequences for the deformation behavior of amorphous solids in
general.
