Orbital Symmetry and Orbital Excitations in High-Tc Superconductors

Oleś, Andrzej M.; Wohlfeld, Krzysztof; Khaliullin, Giniyat

doi:10.3390/condmat4020046

Cited by 18 publications

(12 citation statements)

References 170 publications

(213 reference statements)

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“…Recently, this scenario has also been supported by the investigations on new functional solids by new advanced methods [46,47]. The complexity is driven by cooperative effects of the self organization of dopants discussed in detail in a Special Issue [48], the pseudo Jahan Teller effect involving multiple orbitals [49,50], and local lattice tilts [51]. These results are currently a hot topic, since the strong electron-phonon interaction in complex multi-band materials in extreme conditions near lattice instabilities is emerging as a key mechanism in high-temperature superconductor hydrides [52,53] showing anomalous isotope effect [54,55].…”

Section: Discussionmentioning

confidence: 94%

Scaling between Superfluid Density and Tc in Overdoped La2−xSrxCuO4 Films

Mello

2019

Condensed Matter

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We used an electronic phase separation approach to interpret the scaling between the low-temperature superfluid density average ρ sc ( 0 ) and the superconducting critical temperature T c on overdoped La 2 − x Sr x CuO 4 films. Guided by the observed nematic and incommensurate charge ordering (CO), we performed simulations with a free energy that reproduces charge domains with wavelength λ C O and provides a scale to local superconducting interactions. Under these conditions a complex order parameter with amplitude Δ d ( r i ) and phase θ ( r i ) may develop at a domain i. We assumed that these domains are coupled by Josephson energy E J ( r i j ) , proportional to the local superfluid density ρ sc ( r i j ) . Long-range order occured when the average E J ( T c ) is ∼ k B T c . The linear ρ s c ( 0 ) vs. T c relation was satisfied whenever CO was present, even with almost vanishing charge amplitudes.

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Section: Discussionmentioning

confidence: 94%

Scaling between Superfluid Density and Tc in Overdoped La2−xSrxCuO4 Films

Mello

2019

Condensed Matter

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“…For completeness, we add that, when the full spin-orbit coupling is considered [10], effective entangled pseudospinJ operators replace the sum of spin S and pseudospin T-theJ multiplets then define the ground state and excited states of the system. For instance, spin-orbital entanglement gives the breakdown of singlets and triplets at the Fermi surface in Sr 2 RuO 4 [53][54][55] and their linear combinations decide about the orbital character of the pairing components [56]. We believe that future work will also address the role played by entanglement for the d 4 ions in more detail where the pseudospin could vanish and the magnetic moments are hidden in the ground state but would become active in excited states [57][58][59][60][61].…”

Section: The Model and Basic Questionsmentioning

confidence: 94%

Evolution of Spin-Orbital Entanglement with Increasing Ising Spin-Orbit Coupling

et al. 2020

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Several realistic spin-orbital models for transition metal oxides go beyond the classical expectations and could be understood only by employing the quantum entanglement. Experiments on these materials confirm that spin-orbital entanglement has measurable consequences. Here, we capture the essential features of spin-orbital entanglement in complex quantum matter utilizing 1D spin-orbital model which accommodates SU(2)⊗SU(2) symmetric Kugel-Khomskii superexchange as well as the Ising on-site spin-orbit coupling. Building on the results obtained for full and effective models in the regime of strong spin-orbit coupling, we address the question whether the entanglement found on superexchange bonds always increases when the Ising spin-orbit coupling is added. We show that (i) quantum entanglement is amplified by strong spin-orbit coupling and, surprisingly, (ii) almost classical disentangled states are possible. We complete the latter case by analyzing how the entanglement existing for intermediate values of spin-orbit coupling can disappear for higher values of this coupling.

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“…A special case of the Hamiltonian Equation (1) is realized by the steep band/flat band scenario [11][12][13][14][15][16][55][56][57][58][59][60][61]. This corresponds to a band with itinerant Fermi liquid type character and a localized dispersion-less polaronic one [5][6][7][8]30,[62][63][64][65][66][67]…”

Section: The Steep Band/flat Band Modelmentioning

confidence: 99%

Multi-Band Superconductivity and the Steep Band/Flat Band Scenario

et al. 2019

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The basic features of multi-band superconductivity and its implications are derived. In particular, it is shown that enhancements of the superconducting transition temperature take place due to interband interactions. In addition, isotope effects differ substantially from the typical BCS scheme as soon as polaronic coupling effects are present. Special cases of the model are polaronic coupling in one band as realized e.g., in cuprates, coexistence of a flat band and a steep band like in MgB2, crossovers between extreme cases. The advantages of the multiband approach as compared to the single band BCS model are elucidated and its rather frequent realization in actual systems discussed.

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Orbital Symmetry and Orbital Excitations in High-Tc Superconductors

Cited by 18 publications

References 170 publications

Scaling between Superfluid Density and Tc in Overdoped La2−xSrxCuO4 Films

Scaling between Superfluid Density and Tc in Overdoped La2−xSrxCuO4 Films

Evolution of Spin-Orbital Entanglement with Increasing Ising Spin-Orbit Coupling

Multi-Band Superconductivity and the Steep Band/Flat Band Scenario

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