Mechanism of Slow Relaxation due to Screening Effect in a Frustrated System

TL;DR

This paper investigates a unique slow relaxation phenomenon in frustrated spin systems caused by an entropy-driven screening effect, termed 'entropic slowing down', which differs from energy barrier mechanisms.

Contribution

It introduces and analyzes the concept of entropic slowing down in a frustrated Ising model, providing analytical estimates of relaxation time scales influenced by decoration spins.

Findings

Relaxation time scales increase exponentially with decoration spins.

The phenomenon occurs even without an energy gap, driven by entropy effects.

Scaling behavior of relaxation processes is demonstrated across temperatures.

Abstract

We study a slow relaxation process in a frustrated spin system in which a type of screening effect due to a frustrated environment plays an important role. This screening effect is attributed to the highly degenerate configurations of the frustrated environment. This slow relaxation is due to an entropy effect and is different from those due to the energy barrier observed in systems such as random ferromagnets. In the present system, even if there is no energy gap, the slow relaxation still takes place. Thus, we call this phenomenon ``entropic slowing down''. Here, we study the mechanism of entropic slowing down quantitatively in an Ising spin model with the so-called decorated bonds. The spins included in decorated bonds (decoration spins) cause a peculiar density of states, which causes on entropy-induced screening effect. We analytically estimate the time scale of the system that increases exponentially with the number of decoration spins. We demonstrate the scaling of relaxation processes using the time scale at all temperatures including the critical point.