# Entropic effects in the very-low-temperature regime of diluted Ising spin glasses with discrete couplings

### Thomas Jorg 1, Federico Ricci-Tersenghi 2, 3

#### Physical Review Letters 100 (2008) 177203

We study link-diluted $\pm J$ Ising spin glass models on the hierarchical lattice and on a three-dimensional lattice close to the percolation threshold. We show that previously computed zero temperature fixed points are unstable with respect to temperature perturbations and do not belong to any critical line in the dilution-temperature plane. We discuss implications of the presence of such spurious unstable fixed points on the use of optimization algorithms, and we show how entropic effects should be taken into account to obtain the right physical behavior and critical points.

• 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS),
CNRS : UMR8626 – Université Paris XI - Paris Sud
• 2. Dipartimento di Fisica and INFM,
Università degli studi di Roma I - La Sapienza
• 3. International Centre for Theoretical Physics (ICTP),
the Abdus Salam International Centre for Theoretical Physics