Order-disorder transition in the zero-temperature Ising model on random graphs

TL;DR

This paper investigates the phase transition in the zero-temperature Ising model on random graphs, revealing how the transition point depends on graph density and system size, with implications for network dynamics.

Contribution

It identifies the non-equilibrium order-disorder transition point and characterizes the bistability and absorption times in the model on random graphs.

Findings

Transition point grows with system size

Bimodal distribution of magnetization in absorbing states

Absorption time peaks nonmonotonically with degree

Abstract

The zero-temperature Ising model is known to reach a fully ordered ground state in sufficiently dense random graphs. In sparse random graphs, the dynamics gets absorbed in disordered local minima at magnetization close to zero. Here, we find that the non-equilibrium transition between the ordered and the disordered regime occurs at an average degree that slowly grows with the graph size. The system shows bistability: The distribution of the absolute magnetization in the reached absorbing state is bimodal, with peaks only at zero and unity. For a fixed system size, the average time to absorption behaves nonmonotonically as a function of average degree. The peak value of the average absorption time grows as a power law of the system size. These findings have relevance for community detection, opinion dynamics, and games on networks.