Elbio Dagotto

University of Tennessee at Knoxville

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Co-Authors

Adriana Moreo

University of Tennessee at Knoxville

256

GÁ

Gonzalo Álvarez

Oak Ridge Associated Universities

104

J. Riera

National University of Rosario

Ling-Fang Lin

University of Tennessee at Knoxville

G. B. Martins

Universidade Federal de Uberlândia

Shuai Dong

Southeast University

Yang Zhang

Southeast University

Seiji Yunoki

RIKEN Center for Computational Science

Nitin Kaushal

University of British Columbia

Stephan Haas

University of Southern California

Cooperative Institutions

Oak Ridge National Laboratory

158

University of Tennessee at Knoxville

127

National High Magnetic Field Laboratory

Florida State University

Chinese Academy of Sciences

University of California, Santa Barbara

Argonne National Laboratory

Los Alamos National Laboratory

Centre National de la Recherche Scientifique

Fudan University

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The spatial range of the Kondo effect: a numerical analysis

arXiv (Cornell University) (2009)

C. A. Büsser G. B. Martins L. Costa Ribeiro E. Vernek E. V. Anda

The spatial length of the Kondo screening is still a controversial issue related to Kondo physics. While renormalization group and Bethe Anzats solutions have provided detailed information about the thermodynamics of magnetic impurities, they are insufficient to study the effect on the surrounding electrons, i.e., the spatial range of the correlations created by the Kondo effect between the localized magnetic moment and the conduction electrons. The objective of this work is to present a quantitative way of measuring the extension of these correlations by studying their effect directly on the local density of states (LDOS) at arbitrary distances from the impurity. The numerical techniques used, the Embedded Cluster Approximation, the Finite U Slave Bosons, and Numerical Renormalization Group, calculate the Green functions in real space. With this information, one can calculate how the local density of states away from the impurity is modified by its presence, below and above the Kondo temperature, and then estimate the range of the disturbances in the non-interacting Fermi sea due to the Kondo effect, and how it changes with the Kondo temperature $T_{\rm K}$. The results obtained agree with results obtained through spin-spin correlations, showing that the LDOS captures the phenomenology of the Kondo cloud as well. To the best of our knowledge, it is the first time that the LDOS is used to estimate the extension of the Kondo cloud.

10.48550/arxiv.0906.2951

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Ferroelectricity in a Collinear Magnetic Phase of Orthorhombic Perovskites

Bulletin of the American Physical Society (2007)

И. В. Сергиенко C. Şen Elbio Dagotto

Orthorhombic crystal system

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Constructing quasiparticle operators in strongly correlated systems

World Scientific series in 20th century physics (2002)

Elbio Dagotto J. R. Schrieffer

Dans les modeles a electrons fortement correles, la renormalisation de la fonction d'onde Zh d'un trou infecte dans une bande a moitie remplie est faible par rapport a l'unite. Ce resultat reduit la precision des predictions numeriques et analytiques de la supraconductivite pour les modeles de Hubbard et les modeles associes. Description d'une methode simple pour deduire les operateurs de quasiparticules approches dont Zh est voisine de 1. Test de cette methode pour le modele t-J. On trouve que les operateurs de formation de paires construits a partir de ces quasiparticules sont considerablement ameliores

10.1142/9789812777041_0058

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Nanoscale Phase Separation and Colossal Magnetoresistance: The Physics of Manganites and Related Compounds

Elbio Dagotto Gonzalo Álvarez

1. Why Manganites Are Interesting.- 2. The Discovery of Manganites and the Colossal Magnetoresistance Effect.- 3. Phase Diagrams and Basic Properties of Manganites.- 4. Preliminary Theoretical Considerations: Coulombic and Jahn Teller Effects.- 5. Models for Manganites.- 6. The One-Orbital Model: Phase Diagram and Dominant Correlations.- 7. Monte Carlo Simulations and Application to Manganite Models.- 8. Mean-Field Approximation.- 9. Two-Orbitals Model and Orbital Order.- 10. Charge Ordering: CE-States, Stripes, and Bi-Stripes.- 11. Inhomogeneities in Manganites: The Case of La1?xCaxMnO3.- 12. Optical Conductivity.- 13. Glassy Behavior and Time-Dependent Phenomena.- 14. Inhomogeneities in La1?xSrxMnO3 and Pr1?xCaxMnO3.- 15. Inhomogeneities in Layered Manganites.- 16. An Elementary Introduction to Percolation.- 17. Competition of Phases as the Origin of the CMR.- 18. Pseudogaps and Photoemission Experiments.- 19. Charge-Ordered Nanoclusters above TC: the Smoking Gun of Phase Separation?.- 20. Other Compounds with Large MR and/or Competing FM AF Phases.- 21. Brief Introduction to Giant Magnetoresistance (GMR).- 22. Discussion and Open Questions.- References.

Colossal Magnetoresistance

Manganite

Charge ordering

Percolation (cognitive psychology)

Nanoclusters

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Low-Dimensional Noncollinear Ferroelectricity in Group-VI Oxyhalides

Bulletin of the American Physical Society (2021)

Ling-Fang Lin Yang Zhang Adriana Moreo Elbio Dagotto Shuai Dong

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Phenomenological three-orbital spin-fermion model for cuprates

Physical review. B./Physical review. B (2018)

Mostafa Sherif Derbala Aly Hussein Maria Daghofer Elbio Dagotto Adriana Moreo

A spin-fermion model that captures the charge-transfer properties of Cu-based high critical temperature superconductors is introduced and studied via Monte Carlo simulations. The strong Coulomb repulsion among $d$ electrons in the Cu orbitals is phenomenologically replaced by an exchange coupling between the spins of the itinerant electrons and localized spins at the Cu sites, formally similar to double-exchange models for manganites. This interaction induces a charge-transfer insulator gap in the undoped case (five electrons per unit cell). Adding a small antiferromagnetic Heisenberg coupling between localized spins reinforces the global tendency towards antiferromagnetic order. To perform numerical calculations the localized spins are considered classical as in previous related efforts. In this first paper, undoped and doped $8\ifmmode\times\else\texttimes\fi{}8$ clusters are analyzed in a wide range of temperatures. The numerical results reproduce experimental features in the one-particle spectral function and the density of states, such as: (i) the formation of a Zhang-Rice-like band with a dispersion on the order of $\ensuremath{\sim}0.5\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ and with rotational symmetry about the wave-vector $(\ensuremath{\pi}/2,\ensuremath{\pi}/2)$ at the top of the band and (ii) the opening of a pseudogap at the chemical potential upon doping. We also observed incipient tendencies towards spin incommensurability. This simple model allows for an unbiased study of charge-transfer insulators and offers a formalism intermediate between standard mean-field approximations that fail at finite temperatures in regimes with short-range order and sophisticated quantum Monte Carlo techniques that suffer sign problems.

Mott insulator

Pseudogap

10.1103/physrevb.98.035124

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Kanamori-Moiré-Hubbard model for transition metal dichalcogenide homobilayers

arXiv (Cornell University) (2023)

Nitin Kaushal Elbio Dagotto

Ab-initio and continuum model studies predicted that the $Γ$ valley transition metal dichalcogenide (TMD) homobilayers could simulate the conventional multi-orbital Hubbard model on the moiré Honeycomb lattice. Here, we perform the Wannierization starting from the continuum model and show that a more general Kanamori-Moiré-Hubbard model emerges, beyond the extensively studied standard multi-orbital Hubbard model, which can be used to investigate the many-body physics in the $Γ$ valley TMD homobilayers. Using the unrestricted Hartree-Fock and Lanczos techniques, we study these half-filled multi-orbital moiré bands. By constructing the phase diagrams we predict the presence of an antiferromagnetic state and in addition we found unexepected and dominant states, such as a S = 1 ferromagnetic insulator and a charge density wave state. Our theoretical predictions made using this model can be tested in future experiments on the $Γ$ valley TMD homobilayers.

Charge Density Wave

10.48550/arxiv.2303.02305

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Electronic structure, self-doping, and superconducting instability in the alternating single-layer trilayer stacking nickelates La3Ni2O7

Physical review. B./Physical review. B (2024)

Yang Zhang Ling-Fang Lin Adriana Moreo Thomas Maier Elbio Dagotto

Motivated by the recently proposed alternating single-layer trilayer stacking structure for the nickelate ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$, we comprehensively study this system using ab initio and random-phase approximation techniques. Our analysis unveils similarities between this novel ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$ structure and other Ruddlesden-Popper nickelate superconductors, such as a similar charge-transfer gap value and orbital-selective behavior of the ${e}_{g}$ orbitals. Pressure primarily increases the bandwidths of the Ni ${e}_{g}$ bands, suggesting an enhancement of the itinerant properties of those ${e}_{g}$ states. By changing the cell volume ratio $V/{V}_{0}$ from 0.9 to 1.10, we found that the bilayer structure in ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$ always has lower energy than the single-layer trilayer stacking ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$. In addition, we observe a ``self-doping'' effect (compared to the average 1.5 electrons per ${e}_{g}$ orbital per site of the entire structure) from the trilayer to the single-layer sublattices and this effect will be enhanced by overall electron doping. Moreover, we find a leading ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave pairing state that is restricted to the single layer. Because the effective coupling between the single layers is very weak, due to the nonsuperconducting trilayer in-between, this suggests that the superconducting transition temperature ${T}_{c}$ in this structure should be much lower than in the bilayer structure.

Superconducting transition temperature

10.1103/physrevb.110.l060510

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Citations (3)

Reviews of Modern Physics (1994)

Elbio Dagotto

Theoretical ideas and experimental results concerning high-temperature superconductors are reviewed. Special emphasis is given to calculations performed with the help of computers applied to models of strongly correlated electrons proposed to describe the two-dimensional Cu${\mathrm{O}}_{2}$ planes. The review also includes results using several analytical techniques. The one- and three-band Hubbard models and the $t\ensuremath{-}J$ model are discussed, and their behavior compared against experiments when available. The author found, among the conclusions of the review, that some experimentally observed unusual properties of the cuprates have a natural explanation through Hubbard-like models. In particular, abnormal features like the mid-infrared band of the optical conductivity $\ensuremath{\sigma}(\ensuremath{\omega})$, the new states observed in the gap in photoemission experiments, the behavior of the spin correlations with doping, and the presence of phase separation in the copper oxide superconductors may be explained, at least in part, by these models. Finally, the existence of superconductivity in Hubbard-like models is analyzed. Some aspects of the recently proposed ideas to describe the cuprates as having a ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ superconducting condensate at low temperatures are discussed. Numerical results favor this scenario over others. It is concluded that computational techniques provide a useful, unbiased tool for studying the difficult regime where electrons are strongly interacting, and that considerable progress can be achieved by comparing numerical results against analytical predictions for the properties of these models. Future directions of the active field of computational studies of correlated electrons are briefly discussed.

Copper oxide

10.1103/revmodphys.66.763

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Citations (2,986)

Areas of superconductivity and giant proximity effects in underdoped cuprates

Physical Review B (2005)

Gonzalo Álvarez Matthias Mayr Adriana Moreo Elbio Dagotto

Phenomenological models for the antiferromagnetic (AF) versus $d$-wave superconductivity competition in cuprates are studied using conventional Monte Carlo techniques. The analysis suggests that cuprates may show a variety of different behaviors in the very underdoped regime: local coexistence or first-order transitions among the competing orders, stripes, or glassy states with nanoscale superconducting (SC) puddles. The transition from AF to SC does not seem universal. In particular, the glassy state leads to the possibility of ``colossal'' effects in some cuprates, analog of those in manganites. Under suitable conditions, nonsuperconducting Cu-oxides could rapidly become superconducting by the influence of weak perturbations that align the randomly oriented phases of the SC puddles in the mixed state. Consequences of these ideas for thin-film and photoemission experiments are discussed.

Phenomenological model

10.1103/physrevb.71.014514

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Citations (90)