Strong renormalization of the Fermi-surface topology close to the Mott transition

Tocchio, Luca F.; Becca, Federico; Gros, Claudius

doi:10.1103/physrevb.86.035102

Cited by 26 publications

(31 citation statements)

References 36 publications

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“…By contrast, within the insulating phase, the intra-orbital Jastrow factor is larger than the inter-orbital one, implying that configurations with two electrons on the same orbital are penalized with respect to the ones with two electrons on different orbitals, as expected in the presence of a finite value of J. Only for small values of J/U , a (nearest-neighbor intra-orbital) singlet pairing with d x 2 −y 2 symmetry can be stabilized (see Fig 1), similarly to what occurs in the single-band Hubbard model at half filling [14,48]. Most importantly, a strong (onsite inter-orbital) triplet pairing ∆ ⊥ is stabilized by the presence of a finite Hund coupling, giving a sizable gain in the variational energy with respect to the case with no pairing (see also Sec.…”

Section: Resultsmentioning

confidence: 63%

Metal-insulator transitions, superconductivity, and magnetism in the two-band Hubbard model

2018

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We explore the ground-state properties of the two-band Hubbard model with degenerate electronic bands, parametrized by nearest-neighbor hopping t, intra-and inter-orbital on-site Coulomb repulsions U and U , and Hund coupling J, focusing on the case with J > 0. Using Jastrow-Slater wave functions, we consider both states with and without magnetic/orbital order. Electron pairing can also be included in the wave function, in order to detect the occurrence of superconductivity for generic electron densities n. When no magnetic/orbital order is considered, the Mott transition is continuous for n = 1 (quarter filling); instead, at n = 2 (half filling), it is first order for small values of J/U , while it turns out to be continuous when the ratio J/U is increased. A significant triplet pairing is present in a broad region around n = 2. By contrast, singlet superconductivity (with dwave symmetry) is detected only for small values of the Hund coupling and very close to half filling. When including magnetic and orbital order, the Mott insulator acquires antiferromagnetic order for n = 2; instead, for n = 1 the insulator has ferromagnetic and antiferro-orbital orders. In the latter case, a metallic phase is present for small values of U/t and the metal-insulator transition becomes first order. In the region with 1 < n < 2, we observe that ferromagnetism (with no orbital order) is particularly robust for large values of the Coulomb repulsion and that triplet superconductivity is strongly suppressed by the presence of antiferromagnetism. The case with J = 0, which has an enlarged SU(4) symmetry due to the interplay between spin and orbital degrees of freedom, is also analyzed. arXiv:1805.01856v2 [cond-mat.str-el]

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Section: Resultsmentioning

confidence: 63%

Metal-insulator transitions, superconductivity, and magnetism in the two-band Hubbard model

2018

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“…This is very similar to the case of the two-dimensional single-orbital Hubbard model with including up to the second nearest neighbor hoppings at half filling (n = 1) where the FS of the corresponding |Φ is deformed to the tilted square shape satisfying the perfect nesting condition. 68 When the non-interacting FS of H 0 is far from the square (as in Fig. 1 with additional hole pockets), the metal-insulator transition occurs before the FS deformation is completed with increasing Coulomb interactions.…”

Section: -67mentioning

confidence: 99%

Theoretical study of insulating mechanism in multiorbital Hubbard models with a large spin-orbit coupling: Slater versus Mott scenario inSr2IrO4

2014

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To examine the insulating mechanism of 5d transition metal oxide Sr2IrO4, we study the ground state properties of a three-orbital Hubbard model with a large relativistic spin-orbit coupling on a square lattice. Using a variational Monte Carlo method, we find that the insulating state appearing in the ground state phase diagram for one hole per site varies from a weakly correlated to a strongly correlated antiferromagnetic (AF) state with increasing Coulomb interactions. This crossover is characterized by the different energy gain mechanisms of the AF insulating state, i.e., from an interaction-energy driven Slater-type insulator to a band-energy driven Mott-type insulator with increasing Coulomb interactions. Our calculations reveal that Sr2IrO4 is a "moderately correlated" AF insulator located in the intermediate coupling region between a Slater-type and a Mott-type insulators.

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“…For the single plane, different methods predict that the system becomes a Mott insulator at some finite U, as shown for instance in reference [29], where the critical U was calculated using the dynamical cluster approximation with a variety of cluster sizes. Also, Tocchio et al [30] and Capello et al [31] showed with the VMC method (which in the first reference includes Fermi surface renormalization effects) the appearance of a Mott insulator at a finite U. A possible reason for the occurrence of a Mott insulator for any finite U in reference [9] might be the small cluster size of × 2 2 used in cluster DMFT.…”

Section: ∑∑mentioning

confidence: 99%

The phase diagram of the square lattice bilayer Hubbard model: a variational Monte Carlo study

et al. 2014

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We investigate the phase diagram of the square lattice bilayer Hubbard model at half-filling with the variational Monte Carlo method for both the magnetic and the paramagnetic case as a function of the interlayer hopping ⊥ t and on-site Coulomb repulsion U. With this study we resolve some discrepancies in previous calculations based on the dynamical mean-field theory, and we are able to determine the nature of the phase transitions between metal, Mott insulator and band insulator. In the magnetic case we find only two phases: an antiferromagnetic Mott insulator at small ⊥ t for any value of U and a band insulator at large ⊥ t . At large U values we approach the Heisenberg limit. The paramagnetic phase diagram shows at small ⊥ t a metal to Mott insulator transition at moderate U values and a Mott to band insulator transition at larger U values. We also observe a re-entrant Mott insulator to metal transition and metal to band insulator transition for increasing ⊥ t in the range of < < t U t 5.5 7.5 . Finally, we discuss the phase diagrams obtained in relation to findings from previous studies based on different many-body approaches.

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Strong renormalization of the Fermi-surface topology close to the Mott transition

Cited by 26 publications

References 36 publications

Metal-insulator transitions, superconductivity, and magnetism in the two-band Hubbard model

Metal-insulator transitions, superconductivity, and magnetism in the two-band Hubbard model

Theoretical study of insulating mechanism in multiorbital Hubbard models with a large spin-orbit coupling: Slater versus Mott scenario inSr2IrO4

The phase diagram of the square lattice bilayer Hubbard model: a variational Monte Carlo study

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