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Concept

Mean-field theory

Related publications (29)

Broken-Symmetry Ground States of the Heisenberg Model on the Pyrochlore Lattice

Giuseppe Carleo

The spin-1/2 Heisenberg model on the pyrochlore lattice is an iconic frustrated three-dimensional spin system with a rich phase diagram. Besides hosting several ordered phases, the model is debated to possess a spin-liquid ground state when only nearest-ne ...

American Physical Society2021

Thermal origin of quasilocalized excitations in glasses

Matthieu Wyart, Thomas Willem Jan de Geus, Elisabeth Agoritsas, Marko Popovic, Wencheng Ji

Key aspects of glasses are controlled by the presence of excitations in which a group of particles can rearrange. Surprisingly, recent observations indicate that their density is dramatically reduced and their size decreases as the temperature of the super ...

2020

Concentration of Multi-overlaps for Random Dilute Ferromagnetic Spin Models

Nicolas Macris, Jean François Emmanuel Barbier, Chun Lam Chan

We consider mean field ferromagnetic spin models on dilute random graphs and prove that, with suitable one-body infinitesimal perturbations added to the Hamiltonian, the multi-overlaps concentrate for all temperatures, both with respect to the thermal Gibb ...

SPRINGER2020

Superexchange mechanism and quantum many body excitations in the archetypal di-Cu oxo-bridge

Cédric Weber, Edward Baxter Linscott

The hemocyanin protein binds and transports molecular oxygen via two copper atoms at its core. The singlet state of the Cu2O2 core is thought to be stabilised by a superexchange pathway, but detailed in situ computational analysis is complicated by the mul ...

NATURE PUBLISHING GROUP2020

Dark matter, dark photon and superfluid He-4 from effective field theory

Angelo Esposito

We consider a model of sub-GeV dark matter whose interaction with the Standard Model is mediated by a new vector boson (the dark photon) which couples kinetically to the photon. We describe the possibility of constraining such a model using a superfluid He ...

2020

Magnetic structures and quadratic magnetoelectric effect in LiNiPO4 beyond 30 T

Ellen Fogh

Neutron diffraction with static and pulsed magnetic fields is used to directly probe the magnetic structures in LiNiPO4 up to 25 T and 42 T, respectively. By combining these results with magnetometry and electric polarization measurements under pulsed fiel ...

AMER PHYSICAL SOC2020

Variational phase-field continuum model uncovers adhesive wear mechanisms in asperity junctions

Jean-François Molinari, Sylvain Collet

Wear is well known for causing material loss in a sliding interface. Available macroscopic approaches are bound to empirical fitting parameters, which range several orders of magnitude. Major advances in tribology have recently been achieved via Molecular ...

2020

Dynamical mean-field theory for stochastic gradient descent in Gaussian mixture classification

Lenka Zdeborová, Florent Gérard Krzakala

We analyze in a closed form the learning dynamics of stochastic gradient descent (SGD) for a single layer neural network classifying a high-dimensional Gaussian mixture where each cluster is assigned one of two labels. This problem provides a prototype of ...

Curran Associates, Inc.2020

Exact diagonalization study of the Hubbard-parametrized four-spin ring exchange model on a square lattice

Henrik Moodysson Rønnow, Noore Elahi Shaik, Sofie Janas

We have used exact numerical diagonalization to study the excitation spectrum and the dynamic spin correlations in the s = 1/2 next-next-nearest-neighbor Heisenberg antiferromagnet on the square lattice, with additional four-spin ring exchange from higher- ...

AMER PHYSICAL SOC2019