Competition between crystal field splitting and Hund’s rule coupling in two-orbital magnetic metal-insulator transitions

Quan, Ya‐Min; Zou, Liang‐Jian; Liu, Dayong; Lin, Hai–Qing

doi:10.1140/epjb/e2011-20613-0

Cited by 13 publications

(13 citation statements)

References 16 publications

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“…b α for the doubly occupied state with a pair of up and down spin electrons in the α orbital. t ασ for the triply occupied state with a pair of electrons in the β orbital and an extra σ-spin electron in the α orbital, q for the fully occupied state, respectively 16 .…”

Section: Model Hamiltonian and Methodsmentioning

confidence: 99%

“…Magnetic correlation has profound influences on the groundstate properties and magnetic structures of correlated systems. Previous works showed that spin correlations could considerably affect the magnetic groundstate and magnetic fluctuations of multiorbital Hubbard models [16][17][18][19][20][21] .It remains unkown in recent found Ba 2 CuO 4−δ , what the groundstate magnetic structures of two parent compounds Ba 2 CuO 3 and Ba 2 CuO 3.5 are? Clarifying these problems is important since as a new nonconventional superconductor, magnetic correlations and magnetic fluctuations are rather crucial for superconducting Cooper pairing.…”

Section: Introductionmentioning

confidence: 99%

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Band crossover and magnetic phase diagram of high-Tc superconducting compound Ba2CuO4-δ

Bai,

Quan,

Lin

et al. 2021

Preprint

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We present the influences of electronic and magnetic correlations and doping evolution on the groundstate properties of recently discovered superconductor Ba 2 CuO 4−δ by utilizing the Kotliar-Ruckenstein slave boson method. Starting with an effective two-orbital Hubbard model (Scalapino et al. Phys. Rev. B 99, 224515 (2019)), we demonstrate that with increasing doping concentration, the paramagnetic (PM) system evolves from two-band character to single-band ones around the electron filling n=2.5, with the band nature of the d 3z 2 −r 2 and d x 2 −y 2 orbitals to the d x 2 −y 2 orbital, slightly affected when the electronic correlation U varies from 2 to 4 eV. Considering the magnetic correlations, the system displays one antiferromagnetically metallic (AFM) phase in 2 < n < 2.16 and a PM phase in n > 2.16 at U=2 eV, or two AFM phases in 2 < n < 2.57 and 2.76 < n < 3, and a PM phase in 2.57 < n < 2.76 respectively, at U=4 eV. Our results show that near realistic superconducting state around n=2.6 the intermediate correlated Ba 2 CuO 3,2 should be single band character, and the s-wave superconducting pairing strength becomes significant when U>2 eV, and crosses over to d-wave when U>2.2 eV.

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Section: Model Hamiltonian and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Band crossover and magnetic phase diagram of high-Tc superconducting compound Ba2CuO4-δ

Bai,

Quan,

Lin

et al. 2021

Preprint

Self Cite

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“…In a fully self-consistent model with more parameters and non-degenerate bands, we may expect more complexity to be revealed. Previous work 29 has shown that ground-state calculations can reveal competition between the orbital-selective Mott state (due to very large crystal-field splitting) and an antiferromagnetic Mott insulating state (due to a large J), a transition which is likely first-order 29 .…”

Section: Ground State Energiesmentioning

confidence: 95%

Generalized slave-particle method for extended Hubbard models

Georgescu

Ismail‐Beigi

2015

Phys. Rev. B

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We introduce a set of generalized slave-particle models for extended Hubbard models that treat localized electronic correlations using slave-boson decompositions. Our models automatically include two slave-particle methods of recent interest, the slave-rotor and slave-spin methods, as well as a ladder of new intermediate models where one can choose which of the electronic degrees of freedom (e.g., spin or orbital labels) are treated as correlated degrees of freedom by the slave bosons. In addition, our method removes the aberrant behavior of the slave-rotor model, where it systematically overestimates the importance of electronic correlation effects for weak interaction strength, by removing the contribution of unphysical states from the bosonic Hilbert space. The flexibility of our formalism permits one to separate and isolate the effect of correlations on the key degrees of freedom.

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“…In a half-filled two-orbital system without the Hund's coupling, with increasing correlation, the system undergoes a Mott transition from a paramagnetic (PM) metallic phase into a low-spin band insulator or orbital-Mott phase [5,22,32]. The two orbitals become insulating simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Competing roles of longitudinal and transverse Hund’s terms on Mott transitions

Quan

Wang

et al. 2017

Annals of Physics

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Effects of longitudinal (J Z) and transverse (including spin-flip J X and pair-hopping J P terms) Hund's couplings on Mott transitions of two-orbital Hubbard models are studied by the rotationally invariant salve boson approach. We show that in the half-filled asymmetric systems, the orbital selective Mott phase (OSMP) expands with increasing J X,P /J Z when J X,P /J Z < 1, and has the largest region in the isotropic case (J X,P /J Z = 1) ; and further increasing spin-flip Hund's coupling to J X,P /J Z > 1 may quickly suppress the OSMP state. In other near-half-filled systems, the transverse Hund's coupling favors or unfavors the OSMP state, depending on the electronic correlation strength of the systems. In the quarter-filled and around systems, a small J X,P /J Z < 1 has less effect on Mott transition, while a largeJ X,P /J Z > 1 enhances the electron itineracy and considerably increases the critical correlation strength of the Mott transition both in symmetric and asymmetric systems. These results could be addressed by different spin-orbital states favored by J X ,J P and J Z components, respectively; and the competing longitudinal and transverse Hund's coupling terms lead to most strong quantum fluctuations in the isotropic system.

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Competition between crystal field splitting and Hund’s rule coupling in two-orbital magnetic metal-insulator transitions

Cited by 13 publications

References 16 publications

Band crossover and magnetic phase diagram of high-Tc superconducting compound Ba2CuO4-δ

Band crossover and magnetic phase diagram of high-Tc superconducting compound Ba2CuO4-δ

Generalized slave-particle method for extended Hubbard models

Competing roles of longitudinal and transverse Hund’s terms on Mott transitions

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