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Dynamic magnetic properties of $\mathrm{Y_{0.7}Ca_{0.3}MnO_{3}}$ are reported. The system appears to attain local ferromagnetic order at $T_{\mathrm{SRF}} \approx 70$ K. Below this temperature the low field magnetization becomes history…

Materials Science · Physics 2009-10-31 R. Mathieu , P. Nordblad , D. N. H. Nam , N. X. Phuc , N. V. Khiem

We present a magnetometry, muon spin relaxation ($\mu$SR), and neutron scattering study of the insulating face-centered-cubic spin glass Zn$_{0.5}$Mn$_{0.5}$Te. The magnetometry and $\mu$SR results confirm a spin freezing transition around…

We have investigated a phase transition of a long-range RKKY Ising spin glass \dyyrusi by means of the dc and the ac magnetization measurements. The static nonlinear susceptibility $\chi_{2}$ exhibits a divergent behavior toward $\Tg$ $=$…

Disordered Systems and Neural Networks · Physics 2010-09-21 Y Tabata , K Matsuda , S Kanada , T Waki , H Nakamura , K Sato , K Kindo

We consider the energy difference restricted to a finite volume for certain pairs of incongruent ground states (if they exist) in the d-dimensional Edwards-Anderson (EA) Ising spin glass at zero temperature. We prove that the variance of…

Mathematical Physics · Physics 2016-05-04 L. -P. Arguin , C. M. Newman , D. L. Stein , J. Wehr

We discuss ergodicity breaking in frustrated disordered systems with no apparent broken symmetry of the Hamiltonian and present a way how to amend it in the low-temperature phase. We demonstrate this phenomenon on mean-field models of spin…

Disordered Systems and Neural Networks · Physics 2015-01-09 V. Janis , A. Kauch , A. Klic

We report a Monte Carlo study of the effects of {\it fluctuations} in the bond distribution of Ising spin glasses in a transverse magnetic field, in the {\it paramagnetic phase} in the $T\to 0$ limit. Rare, strong fluctuations give rise to…

Condensed Matter · Physics 2012-08-17 Muyu Guo , R. N. Bhatt , David A. Huse

Understanding the relationship between the heterogeneous structure of complex networks and cooperative phenomena occurring on them remains a key problem in network science. Mean-field theories of spin models on networks constitute a…

Disordered Systems and Neural Networks · Physics 2022-02-10 Fernando L. Metz , Thomas Peron

We consider the random fluctuations of the free energy in the $p$-spin version of the Sherrington-Kirkpatrick model in the high temperature regime. Using the martingale approach of Comets and Neveu as used in the standard SK model combined…

Disordered Systems and Neural Networks · Physics 2007-05-23 A. Bovier , I. Kurkova , M. Loewe

Using Monte Carlo simulations, we study in detail the overlap distribution for individual samples for several spin-glass models including the infinite-range Sherrington-Kirkpatrick model, short-range Edwards-Anderson models in three and…

Disordered Systems and Neural Networks · Physics 2014-10-29 Matthew Wittmann , B. Yucesoy , Helmut G. Katzgraber , J. Machta , A. P. Young

The Griffiths inequalities for Ising spin-glass models with Gaussian randomness of non-vanishing mean are proved using properties of the Gaussian distribution and gauge symmetry of the system. These inequalities imply that correlation…

Disordered Systems and Neural Networks · Physics 2009-11-10 Satoshi Morita , Hidetoshi Nishimori , Pierluigi Contucci

The high temperature limit of interacting spins is usually not associated with ordering or critical phenomena. Nevertheless, spontaneous fluctuations of a local spin polarization at equilibrium have nontrivial dynamics even in this limit.…

Statistical Mechanics · Physics 2023-07-03 V. N. Gorshkov , N. A. Sinitsyn , D. Mozyrsky

We present the experimental observation of the fluctuation-dissipation theorem (FDT) violation in an assembly of interacting magnetic nanoparticles in the low temperature superspin glass phase. The magnetic noise is measured with a…

Disordered Systems and Neural Networks · Physics 2015-05-20 Katsuyoshi Komatsu , D. L'Hote , Sawako Nakamae , Vincent Mosser , Marcin Konczykowski , Emmanuelle Dubois , V. Dupuis , Régine Perzynski

Exact ground states of two-dimensional Ising spin glasses with Gaussian and bimodal (+- J) distributions of the disorder are calculated using a ``matching'' algorithm, which allows large system sizes of up to N=480^2 spins to be…

Disordered Systems and Neural Networks · Physics 2009-11-07 A. K. Hartmann , A. P. Young

We introduce a solvable spherical model of coupled oscillators with fully random interactions and distributed natural frequencies. Using the dynamical mean-field theory, we derive self-consistent equations for the steady-state response and…

Disordered Systems and Neural Networks · Physics 2026-04-07 Harukuni Ikeda

The large amounts of data from molecular biology and neuroscience have lead to a renewed interest in the inverse Ising problem: how to reconstruct parameters of the Ising model (couplings between spins and external fields) from a number of…

Disordered Systems and Neural Networks · Physics 2012-08-13 H. Chau Nguyen , Johannes Berg

We study a cluster Ising model with non-Hermitian external field which can be exactly solved in the language of free fermions. By investigating the second derivative of energy density and fidelity, the possible new critical points are…

Statistical Mechanics · Physics 2022-05-31 Zheng-Xin Guo , Xue-Jia Yu , Xi-Dan Hu , Zhi Li

The high-frequency shear modulus of five Zr-, Pd-, Cu-based conventional and two high-entropy bulk metallic glasses was measured in a wide temperature range up to the beginning of crystallization. Using these data and general thermodynamic…

Disordered Systems and Neural Networks · Physics 2023-06-02 R. A. Konchakov , A. S. Makarov , G. V. Afonin , J. C. Qiao , M. G. Vasin , N. P. Kobelev , V. A. Khonik

We discuss the problem of static chaos in spin glasses. In the case of magnetic field perturbations, we propose a scaling theory for the spin-glass phase. Using the mean-field approach we argue that some pure states are suppressed by the…

Condensed Matter · Physics 2009-10-22 Felix Ritort

Although the fully connected Ising model does not have a length scale, we show that its critical exponents can be found using finite size scaling with the scaling variable equal to N, the number of spins. We find that at the critical…

Statistical Mechanics · Physics 2014-10-15 Louis Colonna-Romano , Harvey Gould , W. Klein

The field theory of a short range spin glass with Gaussian random interactions, is considered near the upper critical dimension six. In the glassy phase, replica symmetry breaking is accompanied with massless Goldstone modes, generated by…

Condensed Matter · Physics 2009-11-07 E. Brézin , C. De Dominicis