Absence of aging in the remanent magnetization in Migdal-Kadanoff spin glasses

TL;DR

This study investigates the non-equilibrium behavior of Migdal-Kadanoff spin glasses, revealing an absence of aging in remanent magnetization, which challenges the applicability of the droplet model to real spin glasses.

Contribution

It demonstrates that the Migdal-Kadanoff approximation does not exhibit aging in remanent magnetization, questioning the droplet model's validity for real spin glasses.

Findings

No aging observed in remanent magnetization

Magnetic viscosity lacks a maximum

Results conflict with experimental and other numerical studies

Abstract

We study the non-equilibrium behavior of three-dimensional spin glasses in the Migdal-Kadanoff approximation, that is on a hierarchical lattice. In this approximation the model has an unique ground state and equilibrium properties correctly described by the droplet model. Extensive numerical simulations show that this model lacks aging in the remanent magnetization as well as a maximum in the magnetic viscosity in disagreement with experiments as well as with numerical studies of the Edwards-Anderson model. This result strongly limits the validity of the droplet model (at least in its simplest form) as a good model for real spin glasses.