The XY Spin-Glass with Slow Dynamic Couplings

TL;DR

This paper studies a dynamic XY spin-glass model where both spins and couplings evolve over time, revealing two distinct spin-glass phases with different freezing behaviors through replica theory analysis.

Contribution

It introduces a novel XY spin-glass model with slow evolving couplings and develops a two-level replica solution to analyze its phase diagram.

Findings

Identification of two spin-glass phases with different order parameters

Existence of two de Almeida-Thouless lines indicating replica-symmetry breaking

Distinct freezing behaviors of spins and couplings in different phases

Abstract

We investigate an XY spin-glass model in which both spins and couplings evolve in time: the spins change rapidly according to Glauber-type rules, whereas the couplings evolve slowly with a dynamics involving spin correlations and Gaussian disorder. For large times the model can be solved using replica theory. In contrast to the XY-model with static disordered couplings, solving the present model requires two levels of replicas, one for the spins and one for the couplings. Relevant order parameters are defined and a phase diagram is obtained upon making the replica-symmetric Ansatz. The system exhibits two different spin-glass phases, with distinct de Almeida-Thouless lines, marking continuous replica-symmetry breaking: one describing freezing of the spins only, and one describing freezing of both spins and couplings.