Doping-driven orbital-selective Mott transition in multi-band Hubbard models with crystal field splitting

Wang, Yilin; Li, Huang; Du, Liang; Dai, Xi

doi:10.1088/1674-1056/25/3/037103

Cited by 9 publications

(8 citation statements)

References 35 publications

(100 reference statements)

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“…Strong electronic correlations may greatly renormalize the electronic spectral distribution, thus affecting the orbital splitting [4][5][6][7]. The crystal field splitting also has a strong influence on the Mott transition in several materials, as it favors orbital polarization and orbital selective phenomena [8][9][10][11][12][13][14][15][16][17].…”

mentioning

confidence: 99%

Extended regime of coexisting metallic and insulating phases in a two-orbital electronic system

Vandelli¹,

Kaufmann²,

V.³

et al. 2022

Preprint

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We investigate the metal-to-insulator phase transition driven by electronic interactions in the quarter-filled Hubbard-Kanamori model on a cubic lattice with two orbitals split by a crystal field. We show that a systematic consideration of the non-local collective electronic fluctuations strongly affects the state-of-the-art picture of the phase transition provided by the dynamical mean field theory. Our calculations reveal a region of phase coexistence between the metallic and the Mott insulating states, which is missing in the local approximation to electronic correlations. This coexistence region is remarkably broad in terms of the interaction strength. It starts at a critical value of the interaction slightly larger than the bandwidth and extends to more than twice the bandwidth, where the two solutions merge into a Mott insulating phase. Our results illustrate that non-local correlations can have crucial consequences on the electronic properties in the strongly correlated regime, even in the simplest multi-orbital systems.c † jlσ t l j j + ∆ l δ j j c j lσ + U 2 j,ll n jl n jl contains three contributions. The hopping t l j j between lattice

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mentioning

confidence: 99%

Extended regime of coexisting metallic and insulating phases in a two-orbital electronic system

Vandelli¹,

Kaufmann²,

V.³

et al. 2022

Preprint

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“…These considerations anticipate the mechanism driving the phase transitions [18][19][20][21][22]53]: ∆ primarily induces orbital polarization; i.e., it changes the relative filling of the orbitals. Starting from the orbitally symmetric, metallic phase, the different orbitals can become bandinsulating or undergo a filling-driven Mott transition.…”

Section: Crystal-field Splittingmentioning

confidence: 97%

“…Whereas different bandwidths directly lead to different effective interaction strengths among the orbitals (as extensively studied for two-orbital models; see, e.g., [17] for a list of references), we focus here on the more intricate case where a crystal field shifts one orbital in energy w.r.t. two degenerate orbitals [18][19][20][21][22]. Thereby, we can isolate polarization effects and drive the system through band+Mott insulating, metallic, and OSM phases, reminiscent of Ca 2 RuO 4 [13], Sr 2 RuO 4 [23], and FeSCs, respectively.…”

Section: Introductionmentioning

confidence: 99%

Orbital differentiation in Hund metals

et al. 2019

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Orbital differentiation is a common theme in multiorbital systems, yet a complete understanding of it is still missing. Here, we consider a minimal model for orbital differentiation in Hund metals with a highly accurate method: We use the numerical renormalization group as a real-frequency impurity solver for a dynamical mean-field study of three-orbital Hubbard models, where a crystal field shifts one orbital in energy. The individual phases are characterized with dynamic correlation functions and their relation to diverse Kondo temperatures. Upon approaching the orbital-selective Mott transition, we find a strongly suppressed spin coherence scale and uncover the emergence of a singular Fermi liquid and interband doublon-holon excitations. Our theory describes the diverse polarization-driven phenomena in the t2g bands of materials such as ruthenates and iron-based superconductors, and our methodological advances pave the way toward real-frequency analyses of strongly correlated materials.

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“…the conventional Hubbard U , as well as of the higher order multipoles responsible of Hund's rules. For instance, the distinction between different orbitals brought about by the hopping integrals and the crystal field can be amplified by strong correlations, leading to pronounced orbital differentiation [7][8][9][10] , and eventually to the so-called orbital-selective Mott transitions (OSMT) [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] where the orbitals with the narrowest bandwidth localise while the others are still itinerant. In addition, orbital degrees of freedom are expected to play an important role in determining which symmetry-broken phase is more likely to accompany the Mott transition when correlations grow at integer electron density.…”

Section: Introductionmentioning

confidence: 99%

Correlation-driven Lifshitz transition and orbital order in a two-band Hubbard model

et al. 2018

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We study by dynamical mean field theory the ground state of a quarter-filled Hubbard model of two bands with different bandwidths. At half-filling, this model is known to display an orbital selective Mott transition, with the narrower band undergoing Mott localisation while the wider one being still itinerant. At quarter-filling, the physical behaviour is different and to some extent reversed. The interaction generates an effective crystal field splitting, absent in the Hamiltonian, that tends to empty the narrower band in favour of the wider one, which also become more correlated than the former at odds with the orbital selective paradigm. Upon increasing the interaction, the depletion of the narrower band can continue till it empties completely and the system undergoes a topological Lifshitz transition into a half-filled single-band metal that eventually turns insulating. Alternatively, when the two bandwidths are not too different, a first order Mott transition intervenes before the Lifshitz's one. The properties of the Mott insulator are significantly affected by the interplay between spin and orbital degrees of freedom.

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Doping-driven orbital-selective Mott transition in multi-band Hubbard models with crystal field splitting

Cited by 9 publications

References 35 publications

Extended regime of coexisting metallic and insulating phases in a two-orbital electronic system

Extended regime of coexisting metallic and insulating phases in a two-orbital electronic system

Orbital differentiation in Hund metals

Correlation-driven Lifshitz transition and orbital order in a two-band Hubbard model

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