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Dilute dipolar Ising magnets remain a notoriously hard problem to tackle both analytically and numerically because of long-ranged interactions between spins as well as rare region effects. We study a new type of anisotropic dilute dipolar…

Disordered Systems and Neural Networks · Physics 2019-08-28 Tushar Kanti Bose , Roderich Moessner , Arnab Sen

Extensive simulations are made on Ising Spin Glasses (ISG) with Gaussian, Laplacian and bimodal interaction distributions in dimension four. Standard finite size scaling analyses near and at criticality provide estimates of the critical…

Disordered Systems and Neural Networks · Physics 2014-08-06 P. H. Lundow , I. A. Campbell

In order to overcome the limitations of small system sizes in spin-glass simulations, we investigate the one-dimensional Ising spin chain with power-law interactions. The model has the advantage over traditional higher-dimensional…

Disordered Systems and Neural Networks · Physics 2009-11-11 Helmut G. Katzgraber , Mathias Koerner , Frauke Liers , A. K. Hartmann

The transverse-field Ising models with random exchange interactions in finite dimensions are investigated by means of a real-space renormalization-group method. The scheme yields the exact values of the critical point and critical exponent…

Disordered Systems and Neural Networks · Physics 2015-06-11 Ryoji Miyazaki , Hidetoshi Nishimori

We present and solve the Replica Symmetric equations in the context of the Replica Cluster Variational Method for the 2D random bond Ising model (including the 2D Edwards-Anderson spin glass model). First we solve a linearized version of…

Disordered Systems and Neural Networks · Physics 2015-06-04 Alejandro Lage-Castellanos , Roberto Mulet , Federico Ricci-Tersenghi , Tommaso Rizzo

We study the existence of a spin-glass phase in a field using Monte Carlo simulations performed along a nontrivial path in the field--temperature plane that must cross any putative de Almeida-Thouless instability line. The method is first…

Disordered Systems and Neural Networks · Physics 2008-05-13 Thomas Jorg , Helmut G. Katzgraber , Florent Krzakala

We use finite size scaling to study Ising spin glasses in two spatial dimensions. The issue of universality is addressed by comparing discrete and continuous probability distributions for the quenched random couplings. The sophisticated…

Disordered Systems and Neural Networks · Physics 2016-07-06 L. A. Fernandez , E. Marinari , V. Martin-Mayor , G. Parisi , J. J. Ruiz-Lorenzo

We study the 4d Heisenberg spin glass model with Gaussian nearest-neighbor interactions. We use finite size scaling to analyze the data. We find a behavior consistent with a finite temperature spin glass transition. Our estimates for the…

Condensed Matter · Physics 2009-10-22 B. Coluzzi

In this talk I will review the approach to spin glasses based on the spontaneously broken replica symmetry. I will concentrate my attention mostly on more general ideas, skipping technical details and stressing the characteristic…

Condensed Matter · Physics 2007-05-23 Giorgio Parisi Dipartimento di fisica Roma

The concept of replica symmetry breaking found in the solution of the mean-field Sherrington-Kirkpatrick spin-glass model has been applied to a variety of problems in science ranging from biological to computational and even financial…

Disordered Systems and Neural Networks · Physics 2008-03-25 Helmut G. Katzgraber , Alexander K. Hartmann , A. P. Young

A theoretical description of the low-temperature phase of short-range spin glasses has remained elusive for decades. In particular, it is unclear if theories that assert a single pair of pure states, or theories that are based infinitely…

Disordered Systems and Neural Networks · Physics 2014-11-14 Wenlong Wang , Jonathan Machta , Helmut G. Katzgraber

We introduce a mean field spin glass model with gaussian distribuited spins and pairwise interactions, whose couplings are drawn randomly from a normal gaussian distribution too. We completely control the main thermodynamical properties of…

Mathematical Physics · Physics 2012-05-18 Adriano Barra , Giuseppe Genovese , Francesco Guerra , Daniele Tantari

The method for calculation of the correlation functions of the Ising-type systems with short-range interaction and with arbitrary value of spin is developed within cluster approximation. For the Ising model (spin $S^z=\pm1$) the expressions…

Condensed Matter · Physics 2007-05-23 R. R. Levitskii , S. I. Sorokov

We present analytical results for the strongly anisotropic random field Ising model, consisting of weakly interacting spin chains. We combine the mean-field treatment of interchain interactions with an analytical calculation of the average…

Statistical Mechanics · Physics 2009-10-31 Marc Thilo Figge , Maxim V. Mostovoy , Jasper Knoester

A dimer mean-field model for the Ising spin-glass is presented. Despite its simplicity it captures some of the essential features of the spin-glass physics. The distribution of the single-spin magnetization is determined from a…

Disordered Systems and Neural Networks · Physics 2009-12-16 Yonatan Dubi , Massimiliano Di Ventra

We give explicit formulas of the Bethe approximation with multipoint correlations for systems with magnetic field. The obtained formulas include the closed form of the magnetization and the correlations between adjacent degrees of freedom.…

Disordered Systems and Neural Networks · Physics 2015-06-16 Masayuki Ohzeki

Ising spin-glass systems with long-range interactions ($J(r)\sim r^{-\sigma}$) are considered. A numerical study of the critical behaviour is presented in the non-mean-field region together with an analysis of the probability distribution…

Disordered Systems and Neural Networks · Physics 2009-10-31 Luca Leuzzi

Infinite-range spin-glass models with Levy-distributed interactions show a spin-glass transition with similarities to both the Sherrington-Kirkpatrick model and to disordered spin systems on finite connectivity random graphs. Despite the…

Disordered Systems and Neural Networks · Physics 2009-11-13 K. Janzen , A. K. Hartmann , A. Engel

Aim of this work is not trying to explore a macroscopic behavior of some recent model in statistical mechanics but showing how some recent techniques developed within the framework of spin glasses do work on simpler model, focusing on the…

Disordered Systems and Neural Networks · Physics 2009-11-13 Adriano Barra

We study the three-spin model and the Ising spin glass in a field using Migdal-Kadanoff approximation. The flows of the couplings and fields indicate no phase transition, but they show even for the three-spin model a slow crossover to the…

Disordered Systems and Neural Networks · Physics 2009-10-31 Barbara Drossel , Hemant Bokil , M. A. Moore