The self-organization and transitions from reversible to irreversible behavior
of interacting particle assemblies—driven by externally imposed stresses or
deformation—are of significant interest in understanding various phenomena in
soft matter. These behaviors have been investigated across diverse systems
such as colloidal suspensions, glasses, and granular materials. Depending on
the density and driving regimes, such transitions are associated with yielding
of amorphous solids, jamming, memory formation, and related phenomena.
However, the interrelation among these behaviors has not been extensively
studied.
To develop a unified view of the different regimes and transitions, we
computationally investigate the response of soft-sphere assemblies to athermal
cyclic-shear deformation over a broad range of densities and deformation
amplitudes. Cyclic-shear deformation induces transitions from reversible to
irreversible behavior in both unjammed and jammed soft-sphere packings. Well
above the minimum isotropic jamming density (ϕ J), this transition corresponds
to yielding.
Near the jamming point and extending up to a higher-density limit (ϕ c y c J),
an unjammed phase appears between a localized absorbing phase and a diffusive,
irreversible phase. This unjammed phase signals a shift of the jamming point
to higher densities due to annealing and introduces a regime where shear
jamming becomes feasible, even for frictionless packings.
Below ϕ J , two distinct localized states—termed point-reversible and
loop-reversible—are observed. We comprehensively characterize these different
regimes and the transitions between them, culminating in a unified
density–shear amplitude phase diagram.
