Orbital-selective Mott transitions in a doped two-band Hubbard model

Jakobi, Eberhard; Blümer, N.; Dongen, Peter van

doi:10.1103/physrevb.80.115109

Cited by 33 publications

(34 citation statements)

References 49 publications

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“…When the low-lying e g orbital (e.g., the x 2 − y 2 in the case of Mn1) on a Mn site becomes half-filled, strong electronic correlations drive an orbital-selective metal-to-insulator transition, with the opening of a Mott gap. Such an orbitalselective Mott transition has been reported before for the Hubbard model, originating from different bandwidth (or correlations) for different orbitals, [56][57][58][59][60][61] or due to the band degeneracy lifting, 62 as well as for materials. [63][64][65] The charge disproportionation between Mn 3+ and Mn 4+ also results in a strong site-selective character of the transition.…”

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confidence: 54%

Tunable site- and orbital-selective Mott transition and quantum confinement effects inLa0.5Ca0.5MnO3nanoclusters

et al. 2015

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We present a dynamical mean-field theory (DMFT) study of the charge and orbital correlations in finite-size La0.5Ca0.5MnO3 (LCMO) nanoclusters. Upon nanostructuring LCMO to clusters of 3 nm diameter, the size reduction induces an insulator-to-metal transition in the high-temperature paramagnetic phase. This is ascribed to the reduction in charge disproportionation between Mn sites with different nominal valence [Das et al., Phys. Rev. Lett. 107, 197202 (2011)]. Here we show that upon further reducing the system size to a few-atom nanoclusters, quantum confinement effects come into play. These lead to the opposite effect: the nanocluster turns insulating again and the charge disproportionation between Mn sites, as well as the orbital polarization, are enhanced. Electron doping by means of external gate voltage on few-atom nanoclusters is found to trigger a site-and orbital-selective Mott transition. Our results suggest that LCMO nanoclusters could be employed for the realization of technological devices, exploiting the proximity to the Mott transition and its control by size and gate voltage.

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confidence: 54%

Tunable site- and orbital-selective Mott transition and quantum confinement effects inLa0.5Ca0.5MnO3nanoclusters

et al. 2015

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“…A few of many-body approaches have been employed to study the paramagnetic Mott transition, such as dynamic mean field theory (DMFT) [1][2][3][4][5][6][7][8] and Kotliar-Ruckenstein slave-boson method 9,10 , etc. With the slave spin technique, Yu and Si recently showed that a paramagnetic orbital insulating phase can exist when the Hund's coupling approaches zero 11 .…”

Section: Introductionmentioning

confidence: 99%

“…Mott-Hubbard metal-insulator transitions (MIT) in multiorbital Hubbard models have been extensively studied since there are rich phase diagrams [1][2][3][4][5][6][7][8][9][10][11][12] . A few of many-body approaches have been employed to study the paramagnetic Mott transition, such as dynamic mean field theory (DMFT) [1][2][3][4][5][6][7][8] and Kotliar-Ruckenstein slave-boson method 9,10 , etc.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2012

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Competition of crystal field splitting and Hund's rule coupling in magnetic metal-insulator transitions of halffilled two-orbital Hubbard model is investigated by multi-orbital slave-boson mean field theory. We show that with the increase of Coulomb correlation, the system firstly transits from a paramagnetic (PM) metal to a Néel antiferromagnetic (AFM) Mott insulator, or a nonmagnetic orbital insulator, depending on the competition of crystal field splitting and the Hund's rule coupling. The different AFM Mott insulator, PM metal and orbital insulating phase are none, partially and fully orbital polarized, respectively. For a small J H and a finite crystal field, the orbital insulator is robust. Although the system is nonmagnetic, the phase boundary of the orbital insulator transition obviously shifts to the small U regime after the magnetic correlations is taken into account. These results demonstrate that large crystal field splitting favors the formation of the orbital insulating phase, while large Hund's rule coupling tends to destroy it, driving the low-spin to high-spin transition.

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“…Classic Mott systems such as VO 2 and NiO contain several d-orbitals that are singly occupied. At present, although there are some studies on Mott transitions in multiorbital systems using dynamical mean-field theory (DMFT) 6,[8][9][10][11] , there is no formalism that describes the spectral weight rearrangements in such systems under doping nor any experiments that observe this effect. In particular, since DMFT neglects the momentum-dependence in the single particle selfenergy, the essential physics of hopping-induced spectral weight transfer under the introduction of dopings can not be captured correctly.…”

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confidence: 99%

Spectral weight transfer in multiorbital Mott systems

Lee

Phillips

2011

Phys. Rev. B

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We develop here a general formalism for multi-orbital Mott systems which can be used to understand dynamical and static spectral weight transfer. We find that the spectral weight transferred from the high energy scales is greatly increased as a result of the multi-orbital structure. As a consequence certainly dynamically generated symmetries obtain at lower values of doping than in the single-band Hubbard model. For example, in the atomic limit, the particle-hole symmetric condition in the lower band shifts from the one-band result of x = 1/3 to x = 1/(2no + 1), where no is the number of orbitals with an unpaired spin. Transport properties computed from effective low-energy theories which forbid double occupancy of bare electrons, such as the multi-orbital t-J generalization, should all be be sensitive to this particle-hole symmetric condition. Away from the atomic limit, the dynamical contributions increase the transferred spectral weight. Consequently, any phenomena which are sensitive to an emergent particle-hole symmetry should obtain at x < (1/(2no + 1).

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Orbital-selective Mott transitions in a doped two-band Hubbard model

Cited by 33 publications

References 49 publications

Tunable site- and orbital-selective Mott transition and quantum confinement effects inLa0.5Ca0.5MnO3nanoclusters

Tunable site- and orbital-selective Mott transition and quantum confinement effects inLa0.5Ca0.5MnO3nanoclusters

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

Spectral weight transfer in multiorbital Mott systems

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