Competition between reduced delocalization and charge transfer effects for a two-band Hubbard model

Nourafkan, Reza; Marsiglio, F.

doi:10.1103/physrevb.84.075133

Cited by 7 publications

(6 citation statements)

References 28 publications

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“…This becomes of increasing importance with reduction of the device dimensions and film thickness. Behavior and interaction of magnetic, lattice, and charge order parameters at the surface can be drastically changed in comparison with the bulk due to symmetry breaking, reduction in number of atomic bonds, and surface atomic reconstructions or extrinsic mechanisms associated with cation nonstoichiometry and structure defects. ,− In turn, catalytic and electrochemical reactions are largely dependent on atomic-scale structure and processes at oxide surfaces . It is apparent that knowledge-based control of Manganite thin film and heterostructure growth with understanding of the atomic-scale mechanism of surface structure formation is necessary.…”

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confidence: 99%

Surface Control of Epitaxial Manganite Films via Oxygen Pressure

et al. 2015

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The trend to reduce device dimensions demands increasing attention to atomic-scale details of structure of thin films as well as to pathways to control it. This is of special importance in the systems with multiple competing interactions. We have used in situ scanning tunneling microscopy to image surfaces of La 5/8 Ca 3/8 MnO 3 films grown by pulsed laser deposition. The atomically resolved imaging was combined with in situ angle-resolved X-ray photoelectron spectroscopy. We find a strong effect of the background oxygen pressure during deposition on structural and chemical features of the film surface. Deposition at 50 mTorr of O 2 leads to mixed-terminated film surfaces, with B-site (MnO 2 ) termination being structurally imperfect at the atomic scale. A relatively small reduction of the oxygen pressure to 20 mTorr results in a dramatic change of the surface structure leading to a nearly perfectly ordered B-site terminated surface with only a small fraction of A-site (La,Ca)O termination. This is accompanied, however, by surface roughening at a mesoscopic length scale. The results suggest that oxygen has a strong link to the adatom mobility during growth. The effect of the oxygen pressure on dopant surface segregation is also pronounced: Ca surface segregation is decreased with oxygen pressure reduction.

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confidence: 99%

Surface Control of Epitaxial Manganite Films via Oxygen Pressure

et al. 2015

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“…Through the addition of an embedding potential in the original Hamiltonian, we succeeded in bringing the effect of the bulk part on the surface. This method leads to a substantial decrease in the time consumed for convergency, and hence, it can be effectively applied in studying the surface of strongly correlated electron models [11,12].…”

Section: Introductionmentioning

confidence: 99%

Electron–Hole Asymmetry Driven Surface Charge Expulsion

Bach

2015

J Low Temp Phys

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We study an Ising-like dynamic Hubbard (IDHB) model using dynamical mean field theory with an embedding potential. The prominent characteristic of the IDHB model is the broken electron-hole symmetry. Our calculations indicate that the electron-hole asymmetry enhances electron expulsion toward the surface of a semi-infinite bulk. Since correlated hopping amplitude produces the electron-hole asymmetry, it strongly affects the electron expulsion toward the surface.

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“…It was shown that the perturbation induced by the surface propagates exponentially deep inside the bulk material with a well-defined length scale which is a function only of bulk properties and not of the strength of the perturbation [4]. Moreover, the effect of the charge transfer from less correlated to more correlated regions has been studied for both single-band and two-band Hubbard models, and it was shown to be more pronounced when an external electric field is applied [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…This in turn gives a hint on the influence of the inter-orbital charge transfer and crystal field effects on the charge transfer from the bulk to the surface. From a theoretical point of view there has been a broad range of studies for inhomogeneous systems, based on single-band [13-15, 6, 16] and multi-band [7] Hubbard models, in order to investigate the effects of surfaces and interfaces. It was found that correlation effects that emerge as propagation of perturbation in the QP weights and the charge transfer play an important role for the understanding of the behavior of the system near the surfaces.…”

Section: Introductionmentioning

confidence: 99%

Surface correlation effects in two-band strongly correlated slabs

Esfahani¹,

Covaci²,

Peeters³

2014

J. Phys.: Condens. Matter

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Using an extension of the Gutzwiller approximation for an inhomogeneous system, we study the two-band Hubbard model with unequal band widths for a slab geometry. The aim is to investigate the mutual effect of individual bands on the spatial distribution of quasi-particle weight and charge density, especially near the surface of the slab. The main effect of the difference in band width is the presence of two different length scales corresponding to the quasi-particle profile of each band. This is enhanced in the vicinity of the critical interaction of the narrow band where an orbitally selective Mott transition occurs and a surface dead layer forms for the narrow band. For the doped case, two different regimes of charge transfer between the surface and the bulk of the slab are revealed. The charge transfer from surface/center to center/surface depends on both the doping level and the average relative charge accumulated in each band. Such effects could also be of importance when describing the accumulation of charges at the interface between structures made of multi-band strongly correlated materials.

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Competition between reduced delocalization and charge transfer effects for a two-band Hubbard model

Cited by 7 publications

References 28 publications

Surface Control of Epitaxial Manganite Films via Oxygen Pressure

Surface Control of Epitaxial Manganite Films via Oxygen Pressure

Electron–Hole Asymmetry Driven Surface Charge Expulsion

Surface correlation effects in two-band strongly correlated slabs

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