34 research outputs found
Following the evolution of glassy states under external perturbations: compression and shear-strain
We consider the adiabatic evolution of glassy states under external
perturbations. Although the formalism we use is very general, we focus here on
infinite-dimensional hard spheres where an exact analysis is possible. We
consider perturbations of the boundary, i.e. compression or (volume preserving)
shear-strain, and we compute the response of glassy states to such
perturbations: pressure and shear-stress. We find that both quantities
overshoot before the glass state becomes unstable at a spinodal point where it
melts into a liquid (or yields). We also estimate the yield stress of the
glass. Finally, we study the stability of the glass basins towards breaking
into sub-basins, corresponding to a Gardner transition. We find that close to
the dynamical transition, glasses undergo a Gardner transition after an
infinitesimal perturbation.Comment: 4 pages (3 figures) + 24 pages (5 pages) of appendice
On the protocol dependence of plasticity in ultra-stable amorphous solids
While perfect crystals may exhibit a purely elastic response to shear all the
way to yielding, the response of amorphous solids is punctuated by plastic
events. The prevalence of this plasticity depends on the number of particles
of the system, with the average strain interval before the first plastic
event, , scaling like with
negative: larger samples are more susceptible to plasticity due to more
numerous disorder-induced soft spots. In this paper we examine this scaling
relation in ultra-stable glasses prepared with the Swap Monte Carlo algorithm,
with regard to the possibility of protocol-dependent scaling exponent, which
would also imply a protocol dependence in the distribution of local yield
stresses in the glass. We show that, while a superficial analysis seems to
corroborate this hypothesis, this is only a pre-asymptotic effect and in fact
our data can be well explained by a simple model wherein such protocol
dependence is absent.Comment: 7 pages, 9 figures; figures improved, implications on the issue of a
static glass lengthscale are discusse