Publications associées à Méthode des répliques

Small-angle neutron scattering study of mesoscale magnetic disordering and skyrmion phase suppression in the frustrated chiral magnet Co6.75Zn6.75Mn6.51

Co-Zn-Mn chiral cubic magnets display versatile magnetic skyrmion phases, including equilibrium phases stable far above and far below room temperature, and the facile creation of robust far-from-equilibrium skyrmion states. In this system, compositional di ...

INT UNION CRYSTALLOGRAPHY2022

The Multi-species Mean-Field Spin-Glass on the Nishimori Line

Emanuele Mingione, Diego Alberici

In this paper we study a multi-species disordered model on the Nishimori line. The typical properties of this line, a set of identities and inequalities among correlation functions, allow us to prove the replica symmetry i.e. the concentration of the order ...

SPRINGER2021

Antiferromagnetic fluctuations and charge carrier localization in ferromagnetic bilayer manganites: electrical resistivity scales exponentially with short-range order controlled by temperature and magnetic field

Gabriel Aeppli

The compound La2-2xSr1+2xMn2O7,x= 0.30-0.40, consists of bilayers of ferromagnetic metallic MnO(2)sheets that are separated by insulating layers. The materials show colossal magnetoresistance-a reduction in resistivity of up to two orders of magnitude in a ...

2020

Annealing and Replica-Symmetry in Deep Boltzmann Machines

Emanuele Mingione, Diego Alberici

In this paper we study the properties of the quenched pressure of a multi-layer spin-glass model (a deep Boltzmann Machine in artificial intelligence jargon) whose pairwise interactions are allowed between spins lying in adjacent layers and not inside the ...

SPRINGER2020

Study of longitudinal fluctuations of the Sherrington-Kirkpatrick model

Lorenzo Talamanca

We study finite-size corrections to the free energy of the Sherrington-Kirkpatrick spin glass in the low-temperature phase where replica symmetry is broken. We investigate the role of longitudinal fluctuations in these corrections, neglecting the transvers ...

IOP PUBLISHING LTD2019

The adaptive interpolation method: a simple scheme to prove replica formulas in Bayesian inference

Nicolas Macris, Jean François Emmanuel Barbier

In recent years important progress has been achieved towards proving the validity of the replica predictions for the (asymptotic) mutual information (or free energy) in Bayesian inference problems. The proof techniques that have emerged appear to be quite ...

SPRINGER HEIDELBERG2019

Simulating frustrated antiferromagnets with quadratically driven QED cavities

Vincenzo Savona, Riccardo Rota

We propose a class of quantum simulators for antiferromagnetic spin systems based on coupled photonic cavities in the presence of two-photon driving and dissipation. By modeling the coupling between the different cavities through a hopping term with negati ...

AMER PHYSICAL SOC2019

Efficient Quantum Monte Carlo simulations of highly frustrated magnets: the frustrated spin-1/2 ladder

Frédéric Mila, Bruce Normand

Quantum Monte Carlo simulations provide one of the more powerful and versatile numerical approaches to condensed matter systems. However, their application to frustrated quantum spin models, in all relevant temperature regimes, is hamstrung by the infamous ...

2017

Synthesis and Physical Properties of 3d, 4d and 5d Transition Metal Compounds

Lin Yang

In this thesis I study the synthesis and basic physical properties characterization on 3

d

, 4

d

and 5

d

transition metal compounds. Great success has been obtained in 3

d

transition metal compounds, in which the electric states are well localized due t ...

EPFL2017

Pressure-tuned Transport Properties of Novel Iron-based Superconductors and Topological Insulators

Andrea Pisoni

The majority of interactions in solids strongly depend on the interatomic distances. The application of pressure changes the lattice parameters and modifies the electronic and the phononic energy spectra of a material avoiding some of the undesirable effec ...

EPFL2016

High pressure induced spin state crossover in Sr2CaYCo4O10.5

Jonathan White

The layered cobaltite Sr2CaYCo4O10.5 with formal average cobalt oxidation state close to 3+ has been studied as functions of both temperature and pressure up to 4GPa by neutron powder diffraction (NPD). The crystal structure is shown to have tetragonal sym ...

Institute of Physics2015

Gallium nitride L3 photonic crystal cavities with an average quality factor of 16 900 in the near infrared

Nicolas Grandjean, Jean-François Carlin, Vincenzo Savona, Raphaël Butté, Matteo Galli, Momchil Minkov, Noelia Vico Triviño

Photonic crystal point-defect cavities were fabricated in a GaN free-standing photonic crystal slab. The cavities are based on the popular L3 design, which was optimized using an automated process based on a genetic algorithm, in order to maximize the qual ...

American Institute of Physics2014

Charge ordering transition in GdBaCo2O5: Evidence of reentrant behavior

Philip Pattison

We present a detailed study on the charge ordering transition in a GdBaCo2O5.0 system by combining highresolution synchrotron powder/single-crystal diffraction with electron paramagnetic resonance experiments as a function of temperature. We found a second ...

Amer Physical Soc2013

Superexchange-Mediated Ferromagnetic Coupling in Two-Dimensional Ni-TCNQ Networks on Metal Surfaces

Klaus Kern, Tzu-Chun Tseng, Violetta Sessi, Nasiba Abdurakhmanova, Christopher Seiji Kley

We investigate the magnetic coupling of Ni centers embedded in two-dimensional metal-coordination networks self-assembled from 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules on Ag(100) and Au (111) surfaces. X-ray magnetic circular dichroism measurement ...

Amer Physical Soc2013

Interacting spin-1 bosons in a two-dimensional optical lattice

We study, using quantum Monte Carlo (QMC) simulations, the ground state properties of spin-1 bosons trapped in a square optical lattice. The phase diagram is characterized by the mobility of the particles (Mott insulating or superfluid phase) and by their ...

Amer Physical Soc2013

Modelling and mathematical results arising from ferromagnetic problems

Jacques Rappaz, Michel Flück, Jean Descloux

In this article, we investigate the equations of magnetostatics for a configuration where a ferromagnetic material occupies a bounded domain and is surrounded by vacuum. Furthermore, the ferromagnetic law takes the form ...

SP Science China Press, Springer2012

Exact Solution of the Gauge Symmetric p-Spin Glass Model on a Complete Graph

Nicolas Macris, Satish Babu Korada

We consider a gauge symmetric version of the p-spin glass model on a complete graph. The gauge symmetry guarantees the absence of replica symmetry breaking and allows to fully use the interpolation scheme of Guerra to rigorously compute the free energy. In ...

2009

Proof of replica formulas in the high noise regime for communication using LDGM codes

Nicolas Macris, Shrinivas Kudekar

We consider communication over a binary input memoryless output symmetric channel with low density generator matrix codes and optimal maximum a posteriori decoding. It is known that the problem of computing the average conditional entropy, over such code e ...

2008

Exact solution for the conditional entropy of Poissonian LDPC codes over the Binary Erasure Channel

Nicolas Macris, Shrinivas Kudekar, Satish Babu Korada

We consider communication over a binary erasure channel with low density parity check codes and optimal maximum a posteriori decoding. It is known that the problem of computing the average conditional entropy, over such code ensembles, in the asymptotic li ...

2007

On the Capacity of a Code Division Multiple Access System

Nicolas Macris, Satish Babu Korada

We consider multiuser communication on a binary input additive white Gaussian noise channel using Randomly Spread-Code Division Multiple Access. We show concentration of various quantities of the system including the capacity and the free energy. We also o ...

2007