Doping-driven metal-insulator transition in correlated electron systems with strong Hund's exchange coupling

Steinbauer, Jakob; Medici, Luca de’; Biermann, Silke

doi:10.1103/physrevb.100.085104

Cited by 9 publications

(3 citation statements)

References 57 publications

(68 reference statements)

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“…The dynamical mean field theory (DMFT) [18] provides the state-of-the-art theoretical description of the Mott transition in realistic materials [19,20]. For instance, this method captures the coexistence of metallic and insulating phases that accompanies the Mott transition in both, single-band [21][22][23][24][25][26][27] and multi-orbital [28][29][30][31][32] systems. However, in some cases DMFT is insufficient, because this theory accounts only for local correlation effects.…”

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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“…In particular, the instantaneous moments increase from 2.3µ B to 2.5µ B , only by less than 9% upon a change of the Hubbard U from 3.8 to 6.9 eV (with J = 0.95 eV). This anomalous dependence of the electronic and magnetic properties of Mn 2 GaC on the Hund's coupling J, with a rather weak dependence on the Hubbard U is reminiscent of that in Hund's metals [67][68][69][70][71][72][73][74][75][76] . We conclude that the magnetic properties of Mn 2 GaC are dictated by its proximity to the regime of formation of local magnetic moments, in which localization is driven by the Hund's exchange coupling J.…”

Section: B Paramagnetic Phasementioning

confidence: 83%

Correlation strength, orbital-selective incoherence, and local moments formation in the magnetic MAX-phase Mn$_2$GaC

Jönsson,

Ekholm,

Leonov

et al. 2022

Preprint

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We perform a theoretical study of the electronic structure and magnetic properties of the prototypical magnetic MAX-phase Mn2GaC with the main focus given to the origin of magnetic interactions in this system. Using the density functional theory+dynamical mean-field theory (DFT+DMFT) method we explore the effects of electron-electron interactions and magnetic correlations on the electronic properties, magnetic state, and spectral weight coherence of paramagnetic and magneticallyordered phases of Mn2GaC. We also benchmark the DFT-based disordered local moment approach for this system by comparing the obtained electronic and magnetic properties with that of the DFT+DMFT method. Our results reveal a complex magnetic behavior characterized by a near degeneracy of the ferro-and antiferromagnetic configurations of Mn2GaC, implying a high sensitivity of its magnetic state to fine details of the crystal structure and unit-cell volume, consistent with experimental observations. We observe robust local-moment behavior and orbital-selective incoherence of the spectral properties of Mn2GaC, implying the importance of orbital-dependent localization of the Mn 3d states. We find that Mn2GaC can be described in terms of local magnetic moments, which may be modeled by DFT with disordered local moments. However, the magnetic properties are dictated by the proximity to the regime of formation of local magnetic moments, in which the localization is in fact driven by the Hund's exchange interaction, and not the Coulomb interaction.

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“…By decreasing ∆ even further, one reenters a metallic (1 < n 1 < 2) and ultimately a band-insulating phase (n 1 = 2). 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: 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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Doping-driven metal-insulator transition in correlated electron systems with strong Hund's exchange coupling

Cited by 9 publications

References 57 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

Correlation strength, orbital-selective incoherence, and local moments formation in the magnetic MAX-phase Mn$_2$GaC

Orbital differentiation in Hund metals

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