Effects of relaxation processes during deposition of anisotropic grains on a flat substrate

TL;DR

This study examines how relaxation processes during the ballistic deposition of anisotropic grains influence the resulting pile structure, including density, magnetization, and percolation transition, with focus on contact energy interactions.

Contribution

It introduces a model of grain deposition with relaxation processes, analyzing their effects on structure and phase transitions, highlighting differences between ferromagnetic and antiferromagnetic interactions.

Findings

Percolation transition from exponential to power-law cluster size.

Relaxation probability q significantly affects density and magnetization.

Differences observed between ferromagnetic and antiferromagnetic contact energies.

Abstract

The ballistic deposition on a one dimensional substrate of grains with one degree of freedom, called spin, is studied with respect to relaxation processes during deposition. The "spin" represents the grain anisotropy, e.g. its longest axis with respect to the vertical. The grains interact through some contact energy (J) and are allowed to flip with a probability q during deposition and relaxation. Different relaxation processes are investigated. The pile structure is investigated, i.e. the density and "magnetisation", as a function of q and J. A percolation transition is found across which the cluster size changes from exponential-like to a power law-like dependence. The differences between "ferromagnetic" and "anti-ferromagnetic"-like contact energies are emphasized as a function of q.