A5047325183- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Quantum and electron transport phenomena
- Theoretical and Computational Physics
- Magnetic and transport properties of perovskites and related materials
- Iron-based superconductors research
- Cold Atom Physics and Bose-Einstein Condensates
- Organic and Molecular Conductors Research
- Quantum many-body systems
- Advanced Chemical Physics Studies
- Advanced Thermodynamics and Statistical Mechanics
- Quantum, superfluid, helium dynamics
- Magnetic properties of thin films
- Rare-earth and actinide compounds
- Complex Systems and Time Series Analysis
- Superconductivity in MgB2 and Alloys
- Spectroscopy and Quantum Chemical Studies
- Inorganic Fluorides and Related Compounds
- Topological Materials and Phenomena
- Graphene research and applications
- stochastic dynamics and bifurcation
- Magnetism in coordination complexes
- Superconducting Materials and Applications
- Algebraic structures and combinatorial models
- Nonlinear Dynamics and Pattern Formation
Université de Sherbrooke
2016-2025
Laboratoire de Chimie et Physique Quantiques
2025
Regroupement Québécois sur les Matériaux de Pointe
2015-2024
Canadian Institute for Advanced Research
2010-2019
Carnegie Mellon University
2010
Institut de Recherche sur les Phénomènes Hors Équilibre
2007
Yale University
2004
Laboratoire des Matériaux Avancés
2000
Simon Fraser University
1990
University of Pennsylvania
1988
Charge transport is a revealing probe of the quantum properties materials. Strong interactions can blur charge carriers resulting in poorly understood "quantum soup". Here we study conductivity Fermi-Hubbard model, testing ground for strong interaction physics, clean system - ultracold $^6$Li 2D optical lattice. We determine diffusion constant our by measuring relaxation an imposed density modulation and modeling its decay hydrodynamically. The converted to resistivity, which exhibits linear...
The Hubbard model represents the fundamental for interacting quantum systems and electronic correlations. Using two-dimensional half-filled at weak coupling as a testing ground, we perform comparative study of comprehensive set state-of-the-art many-body methods. Upon cooling into its insulating antiferromagnetic ground state, hosts rich sequence distinct physical regimes with crossovers between high-temperature incoherent regime, an intermediate-temperature metallic low-temperature regime...
obtained by numerically solving self-consistent integral equations.Detailed comparisons with experimental results on transition-metal oxides have shown that three-dimensional materials can be well described the infinite-dimensional mean-field approach.[11] Other methods, such as slave-boson [12] or slave-fermion [13] approaches, also allowed one to gain insights into Hubbard model through various theories corrected for fluctuations.In this context however, are not based a variational...
New results for the magnitude of flicker noise, considered as resistance fluctuations, in random resistor networks are reported. Near percolation threshold ${p}_{c}$, relative noise is shown to diverge ${(p\ensuremath{-}{p}_{c})}^{\ensuremath{-}\ensuremath{\kappa}}$. The new exponent $\ensuremath{\kappa}$ calculated by various methods: Monte Carlo simulations, effective-medium theory, and position-space renormalization group. Exponents pertaining higher-order cumulants fluctuations also...
We study the evolution of a Mott-Hubbard insulator into correlated metal upon doping in two-dimensional Hubbard model using cellular dynamical mean-field theory. Short-range spin correlations create two additional bands apart from familiar spectral function. Even tiny this causes jump Fermi energy to one these and an immediate momentum-dependent suppression weight at energy. The pseudogap is closely tied existence bands. This suggests strong-coupling mechanism that arises short-range large...
Using cluster perturbation theory, it is shown that the spectral weight and pseudogap observed at Fermi energy in recent Angle Resolved Photoemission Spectroscopy (ARPES) of both electron hole-doped high-temperature superconductors find their natural explanation within t-t'-t''-U Hubbard model two dimensions. The value interaction U needed to explain experiments for electron-doped systems optimal doping weak intermediate coupling regime where t-J inappropriate. At strong coupling,...
A general formulation for the spectral noise ${S}_{R}$ of random linear resistor networks arbitrary topology is given. General calculational methods based on Tellegen's theorem are illustrated one- and two-probe configurations. For self-similar networks, we show existence a new exponent b, member whole hierarchy exponents characterizing size dependence normalized spectrum ${\mathrm{scrS}}_{R}$=${S}_{R}$/${R}^{2}$. shown to lie between fractal dimension d\ifmmode\bar\else\textasciimacron\fi{}...
Using variational cluster perturbation theory we study the competition between $d$-wave superconductivity ($d\mathrm{SC}$) and antiferromagnetism (AF) in $t\mathrm{\text{\ensuremath{-}}}{t}^{\ensuremath{'}}\mathrm{\text{\ensuremath{-}}}{t}^{\ensuremath{'}\ensuremath{'}}\mathrm{\text{\ensuremath{-}}}U$ Hubbard model. Large scale computer calculations reproduce overall ground-state phase diagram of high-temperature superconductors as well one-particle excitation spectra for both hole electron...
We study the Mott transition, antiferromagnetism, and superconductivity in layered organic conductors using cellular dynamical mean-field theory for frustrated Hubbard model. A $d$-wave superconducting phase appears between an antiferromagnetic insulator a metal ${t}^{\ensuremath{'}}/t=0.3--0.7$ or nonmagnetic (spin liquid) ${t}^{\ensuremath{'}}/t\ensuremath{\ge}0.8$, agreement with experiments on including...
Proximity to a Mott insulating phase is likely be an important physical ingredient of theory that aims describe high-temperature superconductivity in the cuprates. Quantum cluster methods are well suited phase. Hence, as step towards quantitative competition between antiferromagnetism (AFM) and d-wave (SC) cuprates, we use Cellular Dynamical Mean Field Theory compute zero temperature properties two-dimensional square lattice Hubbard model. The order parameter found scale like superexchange...
The Langevin formalism that describes fluctuations about thermodynamic equilibrium is extended to study hydrodynamic nonequilibrium steady states. limitations of our generalization are discussed as well the connection between experimental and theoretical quantities which more subtle than in equilibrium. spectrum for Brillouin scattering from a fluid shear flow or temperature gradient simply obtained by methods. latter problem exhibits an asymmetry height peaks inversely proportional square...
An intricate interplay between superconductivity, pseudogap, and Mott transition, either bandwidth driven or doping driven, occurs in materials. Layered organic conductors cuprates offer two prime examples. We provide a unified perspective of this the two-dimensional Hubbard model within cellular dynamical mean-field theory on 2×2 plaquette using continuous-time quantum Monte Carlo method as impurity solver. Both at half filling finite doping, metallic normal state close to insulator is...
SignificanceMost metals display an electron-scattering rate [Formula: see text] that follows at low temperatures, as prescribed by Fermi liquid theory. But there are important exceptions. One of the most prominent examples is "strange" metal regime in overdoped cuprate supercondcutors, which exhibits a linear T dependence scattering reaches putative Planckian limit. Here, using cutting-edge computational approaches, we show T-linear can emerge from Hubbard model temperatures. Our results...
We present reliable many-body calculations for the t-t'-t''-U Hubbard model that explain in detail results of recent angle-resolved photoemission experiments on electron-doped high-temperature superconductors. The origin pseudogap is traced to two-dimensional antiferromagnetic spin fluctuations whose calculated temperature dependent correlation length also agrees with neutron scattering measurements. make specific predictions photoemission, and phase diagram.
Experiments on layered materials call for a study of the influence short-range spin correlations Mott transition. To this end, we solve cluster dynamical mean-field equations Hubbard model plaquette with continuous-time quantum Monte Carlo. The normal state phase diagram as function temperature $T$, interaction strength $U$ and filling $n$ reveals that upon increasing towards insulator, there is surface first-order transition between two metals at non-zero doping. For $T$ above critical end...
The pseudogap refers to an enigmatic state of matter with unusual physical properties found below a characteristic temperature T* in hole-doped high-temperature superconductors. Determining is critical for understanding this state. Here we study the simplest model correlated electron systems, Hubbard model, cluster dynamical mean-field theory find out whether can occur solely because strong coupling physics and short nonlocal correlations. We that sharp crossover between different regimes...
For doped two-dimensional Mott insulators in their normal state, the challenge is to understand evolution from a conventional metal at high doping strongly correlated near insulator zero doping. To this end, we solve cellular dynamical mean-field equations for Hubbard model using plaquette as reference quantum impurity and continuous-time Monte Carlo method solver. The normal-state phase diagram function of interaction strength $U$, temperature $T$, filling $n$ shows that, upon increasing...
Superconductivity in the cuprates exhibits many unusual features. We study two-dimensional Hubbard model with plaquette dynamical mean-field theory to address these features and relate them other normal-state phenomena, such as pseudogap. Previous studies this method found that upon doping Mott insulator at low temperature a pseudogap phase appears. The low-temperature transition between correlated metal higher is first-order. A series of crossovers emerge along Widom line extension...
The properties of a phase with large correlation length can be strongly influenced by the underlying normal phase. We illustrate this studying half-filled two-dimensional Hubbard model using cellular dynamical mean-field theory continuous-time quantum Monte Carlo. Sharp crossovers in mechanism that favors antiferromagnetic correlations and corresponding local density states are observed. These occur at values interaction strength $U$ temperature $T$ controlled normal-state Mott transition.
Although correlated electronic-structure calculations explain very well the normal state of Sr$_2$RuO$_4$, its superconducting symmetry is still unknown. Here we construct spin and charge fluctuation pairing interactions based on state. Correlations significantly reduce ferromagnetic in favor antiferromagnetic fluctuations increase inter-orbital pairing. From normal-state Eliashberg equations, find spin-singlet $d$-wave close to magnetic instabilities. Away from these instabilities, where...
Experiments have shown that the families of cuprate superconductors largest transition temperature at optimal doping also oxygen hole content [D. Rybicki et al., Nat. Commun. 7, 1-6 (2016)]. They a large charge-transfer gap [W. Ruan Sci. Bull. (Beijing) 61, 1826-1832 (2016)], quantity accessible in normal state, is detrimental to superconductivity. We solve three-band Hubbard model with cellular dynamical mean-field theory and show both these observations follow from model. Cuprates play...
The Kane-Mele model is known to show a quantized spin Hall conductivity at zero temperature.Including Hubbard interactions each site leads quantum phase transition an XY antiferromagnet sufficiently high interaction strength.Here, we use the two-particle self-consistent approach (TPSC), which extend include spin-orbit coupling, investigate Kane-Mele-Hubbard finite temperature and half-filling.TPSC weak intermediate coupling capable of calculating frequency-and momentum-dependent self-energy...
It is shown that the Luttinger liquid unstable to arbitrarily small transverse hopping. The crossover temperatures below which either coherent band motion or long-range order start develop can be finite even when spin and charge velocities differ. Explicit scaling relations for one-particle two-particle are derived in terms of hopping, velocities, anomalous exponents. special case infinite-range hopping treated exactly yields a Fermi down $T=0$, unless exponent $\ensuremath{\theta}>1$.
It is shown that the diluted two-dimensional central-force problem belongs to a new class of percolation problems. Geometric properties such as fractal dimension backbone, correlation-length exponent, and connectivity are completely different from those previously studied Explicit calculations backbone construction an algorithm which identifies infinite rigid cluster clearly demonstrate absence singly connected bonds, overwhelming importance loops, long-range nature rigidity.