Metallic glasses (MGs) are a promising engineering material with superb strength.However,theirAchilles heelis their poor ductility in ambient conditions,particularly under tension.Unlike their crystalline counterparts,MGs possess no long-range translational symmetry in their atomic structure.Therefore,conventional plasticity theories based on crystalline defects,such as dislocations,do not directly apply in understanding the origin of their plasticity.In light of the classical shear transformation zone (STZ) models [1,2] (the inset of Fig.1(a)),the occurrence of plasticity in MGs has often been attributed to local atom slip in loosely packed regions that involve hundreds of atoms [3].