Dependence of photoemission spectra on the charge-transfer gap in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CuO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>planes

Bała, Jan; Oleś, Andrzej M.

doi:10.1103/physrevb.58.9408

Cited by 4 publications

(1 citation statement)

References 56 publications

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“…17 To calculate the spectral properties of the entire oxygen-like valence band we consider below a realistic chargetransfer ͑CT͒ model which takes into account Cu(3d x 2 Ϫy 2) and all in-plane oxygen orbitals O(2p , 2p ) playing a dominant role in CuO 2 planes. The -oxygen states ͑hybridized with the ones͒ were included as they were also observed with strong momentum dependence at higher energies in the ARPES experiment by Pothuizen et al 3 Integrating out the d 10 upper and d 8 lower band we derived in previous papers 12, 18 an effective model for the planar oxygen states, however, only approximating the umklapp processes by splitting oxygen bands and not including the p orbitals. As we show below, the proper treatment of these processes is essential to obtain the spectral functions quantitatively comparable with the results of ARPES experiments.…”

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confidence: 99%

Structure of spin polarons in the spin-fermion model forCuO2planes

Bała

Oleś

2000

Phys. Rev. B

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We investigate the spectral functions and various spin-correlation functions relative to the position of the moving oxygen hole in the quantum Néel state formed by copper spins in CuO 2 planes. Solving the problem in a self-consistent Born approximation we have found the spectral functions with the sector of Zhang-Rice states coexisting with higher energy oxygen states, which agree qualitatively with the experimental data in insulating Sr 2 CuO 2 Cl 2 . The antiferromagnetic correlations are reduced in the neighborhood of the hole but remain antiferromagnatic and the correlation functions can exhibit similar dipolar distortions as reported in the context of the t-J model. The spectral weight of the quasiparticle decreases as 1/L with increasing size of L ϫL clusters for the realistic parameters, but remains finite in the thermodynamic limit of CuO 2 planes.

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Section: Introductionmentioning

confidence: 99%

Structure of spin polarons in the spin-fermion model forCuO2planes

Bała

Oleś

2000

Phys. Rev. B

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Mixed singlet‐triplet superconducting state in doped antiferromagnets

Ag¹,

Wróbel

2006

Physica Status Solidi (b)

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We analyze symmetry mixing in the superconducting (SC) order parameter of planar cuprates. The behavior of thermal conductivity observed in some systems doped with magnetic impurities or in some systems exposed to external magnetic field seems to indicate that such symmetry mixing takes place. We discuss this phenomenon in the framework of the spin polaron model (SPM). We assume that antiferromagnetic (AF) correlations, which are at least of short range, tend to confine motion of holes which have been created in the AF spin background. The nature of the propagation of quasiparticles which are hole-like and the nature of the interaction between quasiparticles is determined by a tendency to restore the local AF order. It is known that two holes in the t -J model (tJM) form bound states with d x 2 -y 2 or p-wave symmetry. The d-wave bound state has lower energy and is the ground state. The mixing of d-wave symmetry with p-wave symmetry takes place in the SC order parameter at some range of finite values of the doping parameter. That range lies at the applicability verge of the SPM, where AF correlation are already very short. On the other hand, these correlations may be strengthened by above mentioned external factors, which seems to explain why symmetry mixing is observed in this case.

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Origin of band and localized electron states in photoemission of NiO

2000

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In a variety of model studies it has been shown that the problem of a single hole in a Mott insulator can be quite well addressed by assuming that all that matters is the interaction between the propagating hole and the spin waves of the insulator. NiO has been often taken as the archetypical example of a Mott insulator and recent angular resolved photoemission studies have revealed that holes in this material share both itinerant and localized aspects that are very hard to understand either in conventional band-structure theory or from purely localized approaches. Starting from a strongly coupled electronic multiband Hubbard model, we derive a generalized strong-coupling spin-fermion model. The model includes the multiplet structure of the electronic excitations and describes the interaction of the O(2p) holes moving in oxygen bands with the spins localized on Ni ions. In linear spin-wave order we find an effective Hamiltonian describing the scattering of the bandlike holes on the spin waves. This problem is solved in rainbow order, and we find that the outcomes resemble well the experimental findings. In contrast to earlier impurity interpretations stressing spatial locality, we find that momentum dependencies are dominating the hole dynamics. I. SPIN WAVES AND PHOTOEMISSION OF NiOThe discovery of the high-T c superconductors triggered a revival in the interest of the electronic structure of the transition-metal oxides. Several interesting electronic and magnetic properties observed in these materials are caused by strong electron correlations, driven by the large Coulomb interaction U between the 3d electrons. Not surprisingly, band-structure theory fails in even the most elementary aspects. For instance, the calculations performed within local ͑spin͒ density approximation ͓L͑S͒DA͔ predict that some of the transition-metal oxides ͑such as FeO and CoO͒ are metals, while in reality they are large-gap Mott insulators. Even if the insulating character, as for NiO, is correctly reproduced, the value of the gap is too small by an order of magnitude.1 Some time ago, it seemed that this problem was basically solved in approaches that emphasized the interactions. It was assumed that the physics was essentially local; single electron momentum was supposed to be destroyed completely and instead one could limit the description to ͑atomic͒ interactions and short-range quantum delocalization. In this way the momentum integrated spectral functions could be explained in some detail.2,3 Most importantly, the so-called satellites seen in the photoemission spectra ͑spectral weight showing up at large excitation energies͒, originally discussed in terms of spectroscopic artifacts, were identified to correspond with Hubbard bands, showing that Hubbard models can be taken quite literally, even on energy scales for which they were not intended.Because this ''Hubbard band structure'' was now accessible experimentally, 4,5 surprises followed. It turned out that other bands could show up in between the 3d derived Hubbard bands-in the l...

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Dependence of photoemission spectra on the charge-transfer gap inCuO2planes

Cited by 4 publications

References 56 publications

Structure of spin polarons in the spin-fermion model forCuO2planes

Structure of spin polarons in the spin-fermion model forCuO2planes

Mixed singlet‐triplet superconducting state in doped antiferromagnets

Origin of band and localized electron states in photoemission of NiO

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