Geometrical properties of mechanically annealed systems near the jamming transition

TL;DR

This study investigates how mechanical training affects the geometrical properties, especially hyperuniformity, of 2D particle systems near the jamming transition, revealing non-universal behaviors linked to reversible phases.

Contribution

It demonstrates how mechanical training influences hyperuniformity and phase transitions in systems near jamming, challenging the universality of criticality at the transition.

Findings

Hyperuniformity exponent increases with compression above jamming

Hyperuniformity exponent increases with shear amplitude below jamming

Transition point coincides with change from point-reversible to loop-reversible phase

Abstract

Geometrical properties of two-dimensional mixtures near the jamming transition point are numerically investigated using harmonic particles under mechanical training. The configurations generated by the quasi-static compression and oscillatory shear deformations exhibit anomalous suppression of the density fluctuations, known as hyperuniformity, below and above the jamming transition. For the jammed system trained by compression above the transition point, the hyperuniformity exponent increases. For the system below the transition point under oscillatory shear, the hyperuniformity exponent also increases until the shear amplitude reaches the threshold value. The threshold value matches with the transition point from the point-reversible phase where the particles experience no collision to the loop-reversible phase where the particles' displacements are non-affine during a shear-cycle before coming back to an original position. The results demonstrated in this paper are explained in terms of neither of universal criticality of the jamming transition nor the nonequilibrium phase transitions.