Year: 2015
Type: article
Abstract: Using Monte Carlo simulations, we study the character of the spin-glass (SG) state of a site-diluted dipolar Ising model. We consider systems of dipoles randomly placed on a fraction $x$ of all ${L}^{3}$ sites of a simple cubic lattice that point up or down along a given crystalline axis. For $x\ensuremath{\lesssim}0.65$ these systems are known to exhibit an equilibrium spin-glass phase below a temperature ${T}_{\mathrm{sg}}\ensuremath{\propto}x$. At high dilution and very low temperatures, well deep in the SG phase, we find spiky distributions of the overlap parameter $q$ that are strongly sample dependent. We focus on spikes associated with large excitations. From cumulative distributions of $q$ and a pair correlation function averaged over several thousands of samples we find that, for the system sizes studied, the average width of spikes, and the fraction of samples with spikes higher than a certain threshold, does not vary appreciably with $L$. This is compared with the behavior found for the Sherrington-Kirkpatrick model.
Source: Physical Review B
Author: Juan J. Alonso
Institutions: Universidad de Granada, Universidad de Málaga
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Award: G898593400
OpenAlex ID: W2148350620