Tunable yielding and emergent rheology in amorphous solids with active particle doping

Mechanically stable glasses, notably well-annealed and ultrastable ones, typically exhibit brittle failure through shear-band formation. Whether this localization is an inevitable consequence of annealing or can be dynamically controlled remains unknown. We address this by doping amorphous solids with self-propelled particles that perform run-and-tumble or active Brownian dynamics. Through extensive simulations of a polydisperse model, we show that shear-band formation and propagation are governed by a competition among three timescales: the imposed shear time $$1/\dot{\gamma }$$, the activity persistence time τp, and the intrinsic time for a shear band to span the system. At low persistence time, active doping progressively converts a single system-spanning shear band into a network of shear bands, yielding continuously with increased yield stress and yield strain, and inter-band spacing that decreases as a power law with active force. Interestingly, we uncover a universal compensatory relationship between active forces and global shear rates: a rise in one offsets a decline in the other, arising from isomorphic-like behavior across force–strain-rate combinations. We further identify a non-monotonic relationship between yielding and persistence time: while the yield stress increases at small τp with increasing active forces, it tends to decrease at large τp. Under creep, increasing active force reduces the steady-state strain rate and delays fluidization, extending the compensation to the stress-controlled regime. These results establish that shear localization in brittle glasses is not dictated solely by preparation history but can be dynamically altered through internal activity, with broad implications for yielding in living and synthetic active matter. It is known that well-annealed and ultrastable glasses tend to fail abruptly via shear-band formation, with their brittle nature influenced by preparation history and loading conditions. Here, the authors report that doping such amorphous solids with active particles can dynamically control yielding behavior, leading to increased mechanical stability, rounded stress responses, and the emergence of multiple shear bands, governed by a universal interplay of shear rate, active force, and persistence time.