Article
Materials Science, Multidisciplinary
Huu-Nha Nguyen, Van-Nham Phan
Summary: In this study, the low-frequency dynamical magnetic properties in paramagnetic diluted magnetic semiconductors are investigated using the dynamical mean-field theory. Self-consistent equations are derived to evaluate the single-particle Green's function and its self-energy numerically in the infinite-dimensional limit. Based on the Green's function and self-energies, the local dynamical spin susceptibility function and spin-relaxation rate are expressed explicitly using the Baym-Kadanoff approach. The results reveal the dominant role of spin fluctuations in systems with large magnetic coupling and temperature close to the paramagnetic-ferromagnetic transition point.
Article
Physics, Multidisciplinary
Marco Baity-Jesi, Enrico Calore, Andres Cruz, Luis Antonio Fernandez, Jose Miguel Gil-Narvion, Isidoro Gonzalez-Adalid Pemartin, Antonio Gordillo-Guerrero, David Iniguez, Andrea Maiorano, Enzo Marinari, Victor Martin-Mayor, Javier Moreno-Gordo, Antonio Munoz-Sudupe, Denis Navarro, Ilaria Paga, Giorgio Parisi, Sergio Perez-Gaviro, Federico Ricci-Tersenghi, Juan Jesus Ruiz-Lorenzo, Sebastiano Fabio Schifano, Beatriz Seoane, Alfonso Tarancon, Raffaele Tripiccione, David Yllanes
Summary: This study reveals the presence of dynamic temperature chaos in non-equilibrium dynamics, closely resembling equilibrium temperature chaos. The dynamic temperature chaos effect is shown to be controlled by the spin-glass coherence length xi.
COMMUNICATIONS PHYSICS
(2021)
Article
Physics, Multidisciplinary
M. Schmidt, P. F. Dias
Summary: The correlated cluster mean-field (CCMF) theory is an approximate method that has been applied to study spin-1/2 Hamiltonians and extended to Ising-like systems with spin S > 1/2. Research shows that the CCMF method results on honeycomb, square, and simple cubic lattices can be compared to state-of-the-art methods, and applications for higher spin and mixed-spin systems on the honeycomb lattice have been compared with other techniques. Results indicate that the reduced critical temperature obtained within the CCMF theory overestimates by only 5% the exact result for the mixed spin-(1, 1/2) system.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2021)
Article
Physics, Fluids & Plasmas
Federico Ghimenti, Frederic van Wijland
Summary: In this study, we examine a dynamics that violates detailed balance and find that it converges faster than its equilibrium counterpart. By studying a system with energy barriers, we discover that the convergence is accelerated in the nonergodic phase. We also provide an interpretation in terms of trajectories in phase space and an accidental fluctuation-dissipation theorem.
Article
Mathematics, Interdisciplinary Applications
Yigit Ertac Pektas, E. Can Artun, A. Nihat Berker
Summary: The characteristics of a spin-glass system with a smooth or fractal outer surface were studied using renormalization-group theory. The study found that the spin-glass ordering on the smooth surface is different in the presence or absence of bulk spin-glass ordering, while the fractal surface always exhibits spin-glass ordering.
CHAOS SOLITONS & FRACTALS
(2023)
Article
Materials Science, Multidisciplinary
Sourav Chakraborty, Sandip Halder, Kalpataru Pradhan
Summary: We investigate itinerant ferromagnetism using a diluted spin-fermion model derived from a repulsive Hubbard model. The model describes itinerant fermions coupled antiferromagnetically to spin auxiliary fields in a three-dimensional simple cubic lattice. We assign a positive finite value to the Hubbard on-site potential at a fraction of sites to mimic magnetic impurities. By considering positional disorder of the auxiliary fields, our results show that the carrier spins' ferromagnetic transition temperature exhibits an optimization behavior with the carrier density, similar to experimental observations in diluted magnetic semiconductors. The system is found to be a half-metallic ferromagnet based on the calculated spin-polarized resistivities and density of states. Overall, our results provide significant insights into the understanding of ferromagnetism in diluted magnetic semiconductors.
Article
Physics, Mathematical
Mitia Duerinckx
Summary: This study analyzes a system of classical particles and provides sharp estimates on many-particle correlation functions. By proposing a novel non-hierarchical approach, the BBGKY hierarchy can be truncated to any precision on the mean-field timescale, thereby justifying the Bogolyubov corrections to mean field. As a result, a quantitative central limit theorem for fluctuations of the empirical measure is derived, and the Lenard-Balescu limit for a spatially homogeneous system away from thermal equilibrium is discussed.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2021)
Article
Physics, Condensed Matter
Mouli Roy Chowdhury, Mohindar S. Seehra, Prativa Pramanik, Sayandeep Ghosh, Tapati Sarkar, Bruno Weise, Subhash Thota
Summary: The nature of magnetism in the doubly-diluted spinel ZnTiCoO4 = (Zn2+)( A ) [Ti4+Co2+]( B )O-4 is reported here. The study reveals the spin-glass state in ZnTiCoO4 below the spin glass freezing temperature T (SG) = 12.9 K. The field dependence of T (SG) and the magnetic phase diagram in the H-T plane are established.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Materials Science, Multidisciplinary
Yuanji Xu, Yutao Sheng, Yi-feng Yang
Summary: By combining density functional theory and dynamical mean-field theory, it is shown that NaYbSe2 undergoes an insulator-to-metal transition under pressure, followed by the emergence of superconductivity. The transition is a two-stage process, with superconductivity appearing in the heavy-fermion phase.
NPJ QUANTUM MATERIALS
(2022)
Article
Physics, Multidisciplinary
Manaka Okuyama, Masayuki Ohzeki
Summary: Recently, Mori (2011 Phys. Rev. E 84 031128) conjectured that the free energy of Ising spin glass models with the Kac potential in the non-additive limit is equal to that of the Sherrington-Kirkpatrick model in the thermodynamic limit. In this study, we prove his conjecture on the Nishimori line at any temperature in any dimension by using the Gibbs-Bogoliubov inequality. We also discuss the symmetric case of the probability distribution of the interaction, where his conjecture is true in one dimension but open in two or more dimensions in the low-temperature regime.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2023)
Article
Physics, Condensed Matter
Mounirou Karimou, C. M. Salgado, A. S. de Arruda
Summary: The effects of random single-ion anisotropy and random magnetic field on the phase diagram and thermodynamic properties of the spin-7/2 Blume-Capel model were investigated using the Curie-Weiss mean-field approximation. Phase diagrams were presented in the temperature versus single-ion anisotropy, temperature versus magnetic field, and temperature versus random parameters planes. The dependencies of magnetization on temperature and single-ion anisotropy were studied.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Materials Science, Multidisciplinary
Manuel Weber
Summary: We have presented an exact quantum Monte Carlo method that can simulate spin systems coupled to dissipative bosonic baths. This method uses nonlocal wormhole updates to simulate the retarded spin-flip interactions originating from an off-diagonal spin-boson coupling and can be applied to impurity systems and lattice models in any spatial dimension.
Article
Chemistry, Multidisciplinary
Emil Burzo, Romulus Tetean
Summary: The magnetic properties of nanocrystalline MxFe3-xO4 ferrites were investigated, supporting a core-shell model with ferrimagnetic core and spin glass shell behavior. The field dependence of reduced magnetizations and magnetoresistances were analyzed, showing strong correlations with exchange interactions and identical b values for similar nanoparticles compositions.
Article
Materials Science, Multidisciplinary
Damian Tomaszewski, Piotr Busz, Jan Martinek
Summary: This paper provides a detailed theoretical description of the influence of spin accumulation in metallic Fermi leads on the Kondo effect in systems such as quantum dots and Kondo alloys. The study shows that the presence of spin accumulation, magnetic field, and ferromagnetic leads spin polarization can suppress the Kondo effect, but for appropriately selected parameter values, these effects can compensate each other and may lead to the restoration of the Kondo effect in the analyzed systems. The paper also discusses recent experiments related to spin current in Kondo alloys.
Article
Physics, Multidisciplinary
Feng Liu, Zhenhao Fan, Zhipeng Sun, Xuzong Chen, Dingping Li
Summary: The systematic non-perturbative method developed based on Dyson-Schwinger theory and the derivable theory for Ising model at broken phase allows for obtaining critical temperature and spin spin correlation beyond mean field theory. The gapless spectrum of Green function obtained from this method at critical point results in divergent susceptibility at T-c. The critical temperature of Ising model obtained from this method is fairly good compared to other non-cluster methods and can be extended to more complex spin models with continuous symmetry.
FRONTIERS OF PHYSICS
(2021)
Article
Mechanics
I Paga, Q. Zhai, M. Baity-Jesi, E. Calore, A. Cruz, L. A. Fernandez, J. M. Gil-Narvion, I Gonzalez-Adalid Pemartin, A. Gordillo-Guerrero, D. Iniguez, A. Maiorano, E. Marinari, V Martin-Mayor, J. Moreno-Gordo, A. Munoz-Sudupe, D. Navarro, R. L. Orbach, G. Parisi, S. Perez-Gaviro, F. Ricci-Tersenghi, J. J. Ruiz-Lorenzo, S. F. Schifano, D. L. Schlagel, B. Seoane, A. Tarancon, R. Tripiccione, D. Yllanes
Summary: The research focuses on a microscopic analysis of spin-glass dynamics through experiments and simulations, with a particular emphasis on the evolution of spin-glass correlation length at different times and temperatures.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2021)
Article
Multidisciplinary Sciences
M. Leonetti, E. Hormann, L. Leuzzi, G. Parisi, G. Ruocco
Summary: Studying the dynamics of spin glass models is a complex and nondeterministic problem. Researchers have implemented optical simulation to study the spin glass system and demonstrate transitions between different phases. Optical SG offers computational advantages with parallel measurements, leading to speedup in calculations.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Physics, Multidisciplinary
Maria Chiara Angelini, Carlo Lucibello, Giorgio Parisi, Gianmarco Perrupato, Federico Ricci-Tersenghi, Tommaso Rizzo
Summary: This study analyzes the spin-glass transition in finite dimension at zero temperature, revealing crucial differences with classical results such as the upper critical dimension D-U >= 8 for mean-field theory failure.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Silvio Franz, Flavio Nicoletti, Giorgio Parisi, Federico Ricci-Tersenghi
Summary: In this study, we investigate the energy minima of a fully-connected m-components vector spin glass model in an external magnetic field, and study the transition from paramagnetic phase to spin glass phase. The spectral properties of the model are examined and it is found that the spectrum is gapless with pseudo-gap. Despite the long-range nature of the model, the eigenstates close to the edge of the spectrum display quasi-localization properties.
Article
Physics, Multidisciplinary
Jacopo Niedda, Giacomo Gradenigo, Luca Leuzzi, Giorgio Parisi
Summary: By using enhanced Monte Carlo numerical simulations parallelized on GPUs, we investigate the critical properties of the spin-glass-like model for the mode-locked glassy random laser. With two different boundary conditions for the mode frequencies, we determine the critical points and critical indices of the random lasing phase transition using finite size scaling techniques. The scaling analysis reveals that the mode-locked random laser universality class is compatible with a mean-field one, but differs from the mean-field class of the Random Energy Model and the glassy random laser in the narrow band approximation.
Article
Multidisciplinary Sciences
Luca Bindi, Giorgio Parisi
Summary: In this article, the history of quasicrystals is briefly reviewed, and the Topical collection on Quasicrystals: State of the art and outlooks is introduced. This collection includes a number of review articles published in a conference held at the Accademia dei Lincei in November 2022.
RENDICONTI LINCEI-SCIENZE FISICHE E NATURALI
(2023)
Article
Materials Science, Multidisciplinary
Gianmarco Perrupato, Maria Chiara Angelini, Giorgio Parisi, Federico Ricci-Tersenghi, Tommaso Rizzo
Summary: In this study, we investigate the replica symmetry broken phase of spin glass models in a random field and derive a closed equation for the extreme values of the cavity fields. We find that the spontaneous RSB does not occur uniformly in the whole system and is independent of the parameters defining the RSB.
Article
Physics, Fluids & Plasmas
Claudia Artiaco, Rafael Diaz Hernandez Rojas, Giorgio Parisi, Federico Ricci-Tersenghi
Summary: This study presents the CALiPPSO algorithm for investigating the jamming transition of hard spheres. By treating the jamming problem as a constrained optimization problem, the algorithm is able to produce jammed hard sphere packings without using effective potentials. The algorithm is found to generate jammed packings that are always isostatic and in mechanical equilibrium. Extensive numerical simulations demonstrate that the algorithm can successfully probe the complex structure of the free-energy landscape and shows qualitative agreement with mean-field predictions. An open-source implementation of the algorithm is also provided.
Article
Astronomy & Astrophysics
Ludovico T. Giorgini, Ulrich D. Jentschura, Enrico M. Malatesta, Giorgio Parisi, Tommaso Rizzo, Jean Zinn-Justin
Summary: In this study, we verify the obtained analytic results for the O(N)-anharmonic oscillator by numerical calculations of higher-order coefficients. We demonstrate a significant improvement in the agreement between large-order asymptotic estimates and perturbation theory when incorporating two-loop corrections to the large-order behavior.
Article
Physics, Fluids & Plasmas
L. A. Fernandez, I. Gonzalez-Adalid Pemartin, V. Martin-Mayor, G. Parisi, F. Ricci-Tersenghi, T. Rizzo, J. J. Ruiz-Lorenzo, M. Veca
Summary: A growing body of evidence confirms the tenets of Bray and Roberts's theory by studying the Ising spin glass and its correlation length.
Article
Materials Science, Multidisciplinary
Tommaso Rizzo
Summary: The article discusses computating the exponentially small probability of a system jumping from one metastable state to another, focusing on the evaluation of path integrals using mean-field models and saddle-point methods, and solving the resulting dynamical equations with numerical algorithms.
Article
Physics, Fluids & Plasmas
S. Caracciolo, R. Fabbricatore, M. Gherardi, R. Marino, G. Parisi, G. Sicuro
Summary: This paper investigates the effect of localized perturbations on the solution of the random dimer problem in two dimensions, finding that a local perturbation of the optimal covering induces an extensive excitation with finite probability. The statistical properties of excitations in random dimer problems differ on bipartite and nonbipartite lattices, with evidence of conformal invariance compatible with SLE kappa, depending on the bipartiteness of the lattice.
Article
Optics
Claudia Artiaco, Federico Balducci, Giorgio Parisi, Antonello Scardicchio
Summary: By analyzing the quantum dynamics of the perceptron model, we found that the jamming transition in quantum dynamics exhibits critical exponents different from the classical case, and is not confined to the zero-temperature axis. These findings have implications for the theory of glasses at ultralow temperatures and for the study of quantum machine-learning algorithms.
Article
Chemistry, Physical
Rafael Diaz Hernandez Rojas, Giorgio Parisi, Federico Ricci-Tersenghi
Summary: The study focuses on the dynamics near the jamming point and the connection between local structure and particle-wise dynamics, by constructing structural variables and statistically characterizing particle trajectories based on numerical simulations. The dynamical regime is dominated by anharmonic effects, and the slow decay of correlations suggests a universal rate of information loss.
