Electronic pseudogap of optimally doped high-temperature<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Nd</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">Ce</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mi mathvariant="normal">Cu</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>superconductors

Sunko, D. K.; Barišić, S.

doi:10.1103/physrevb.75.060506

Cited by 14 publications

(19 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The SDW wavevector q SDW is close [21] to the antiferromagnetic (AF) q AF . If phonons are not invoked the bosonlike excitations which mediate the attractive interaction are paramagnons [22,23], which generate magnons for low frequencies. Such an attraction is independent of the ionic mass.…”

Section: Small U D Theorymentioning

confidence: 99%

Approaching Large U d High-T c Cuprates from the Covalent Side

Barišić

2012

J Supercond Nov Magn

Self Cite

View full text Add to dashboard Cite

Large U d theories of high-T c cuprates often start from the ionic limit in which one charge per CuO 2 unit cell is localized on the copper site and involved in AF correlations with neighboring sites. AF correlations are promoted by a relatively small exchange J and the motion of holes by is described by the t-J models with narrow effective bands. However, very small hole doping is sufficient to destabilize the Mott-AF phase and the resulting metallic phase explicitly exhibits comparatively wide covalent bands. After a brief description of the large U d ionic limit, the large U d covalent limit is therefore considered. It is shown that in this limit, the large U d produces a reasonably small effective kinematic interaction between two holes on oxygens. This interaction gives rise to magnetic correlations, similar to those found in the weak-coupling Hubbard theories. The distinct signature of large U d is the broadening of the single (and two) particle properties of the system, which is related to the "mixed valence fluctuations" between Cu and 2O, localized within the CuO 2 unit cell. These fluctuations produce a sizeable Landau-like damping of the single (and two) particle propagations, thus competing with the magnetic coherence, characterized by an incommensurate wave-vector. The cuprates appear to fall between these two extreme limits, which might explain in part why they are so difficult to understand.

show abstract

Section: Small U D Theorymentioning

confidence: 99%

Approaching Large U d High-T c Cuprates from the Covalent Side

Barišić

2012

J Supercond Nov Magn

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, the present study indicates that the band parameters are not modified significantly by the reduction process. Moreover, the antinodal LEG in this scenario would be more likely an indirect consequence of magnetic fluctuations such as paramagnons [16]. The lack of theoretical study on the subject leaves open the possibility that charge disorder induced by oxygen vacancies can suppress the AF order and promote superconductivity.…”

mentioning

confidence: 99%

Competition between Antiferromagnetism and Superconductivity in the Electron-Doped Cuprates Triggered by Oxygen Reduction

Richard

Neupane

et al. 2007

Phys. Rev. Lett.

View full text Add to dashboard Cite

We have performed a systematic angle-resolved photoemission study of as-grown and oxygenreduced Pr2−xCexCuO4 and Pr1−xLaCexCuO4 electron-doped cuprates. In contrast to the common belief, neither the band filling nor the band parameters are significantly affected by the oxygen reduction process. Instead, we show that the main electronic role of the reduction process is to remove an anisotropic leading edge gap around the Fermi surface. While the nodal leading edge gap is induced by long-range antiferomagnetic order, the origin of the antinodal one remains unclear.PACS numbers: 74.72. Jt, 74.25.Jb, 74.62.Dh, Even though most of the work has been focused on hole-doped cuprates, the understanding of their electrondoped counterparts is essential for obtaining a universal picture of high-Tc superconductivity. To achieve this goal, it is necessary to first solve the main mystery that holds since the discovery of the T'-structure electrondoped cuprates RE 2−x Ce x CuO 4 and RE 1−x LaCe x CuO 4 (RE = Pr, Nd, Sm, Eu): why is superconductivity in these compounds achieved only when a tiny amount of oxygen (∼ 1%) is removed from the as-grown (AG) samples following a post-annealing process (reduction) [1,2,3,4,5]? In fact, the AG samples, even with sufficient electron-doping by adding Ce, are antiferromagnetic (AF) insulators at low temperature. Far from being a simple materials issue, the understanding of the microscopic origin of the reduction process that triggers superconductivity may shed light on other related questions in high-Tc superconductivity.Long considered as the microscopic explanation of the reduction process, the removal of extraneous oxygen atoms located above Cu (apical oxygen) has been ruled out by recent Raman and crystal-field infrared transmission studies [6,7]. Indeed, these studies revealed two main defects appearing with the oxygen reduction, which have been tentatively assigned to out-of-plane and inplane oxygen vacancies, the latter being the only one observed at optimal doping. In parallel, a (RE,Ce) 2 O 3 impurity phase epitaxial to the CuO 2 planes appears in reduced superconducting samples but disappears in reoxygenated nonsuperconducting samples [8,9,10,11]. Based on this phenomenon, it has been proposed recently that the Cu excess released during the formation of the (RE,Ce) 2 O 3 impurity phase fills Cu vacancies and makes the remaining structure more stoichiometric [11]. Which of these structural defects has the most significant impact on the electronic properties is still under intense debate * Electronic address: richarpi@bc.edu and calls for a better characterization of the electronic band structure before and after the reduction process. In contrast to the widespread belief that the reduction process in the electron-doped cuprates can be considered as an independent degree of freedom for carrier doping, a recent systematic study of the Hall coefficient in Pr 2−x Ce x CuO 4 thin films with various oxygen contents showed that the carrier mobility rather than their concentration is modifie...

show abstract

“…It has long been established that ARPES fits require significant ratios of |t pp /t pd | in order to agree with the data [11]. Recently there appeared detailed ARPES fits, both qualitatively and quantitatively in accord with experiment, in practically the same orbital regime for NCCO [17] and BSCCO [16], which established the anticrossing regime (2) as an appropriate phenomenology for these compounds, meaning the ratio |t pp |/∆ pd is also enhanced, especially so on the electron-doped side.…”

Section: Discussionmentioning

confidence: 73%

Destabilization of the Zhang-Rice singlet at optimal doping

Sunko

2009

J. Exp. Theor. Phys.

Self Cite

View full text Add to dashboard Cite

The construction of the Zhang-Rice singlet is revisited in the light of recent understanding of high-temperature superconductors at optimal doping. A minimal local model is derived which contains the physical regime found relevant for ARPES experiments, characterized by significant direct oxygen-oxygen hopping. For the values of orbital parameters indicated by experiment, the Zhang-Rice singlet is strongly mixed with a pure oxygen singlet of the same symmetry. The destabilization of the Zhang-Rice ground state is due to the oxygen singlet having twice as large a coherence factor with respect to oxygen-oxygen hopping. An analogous quantum phase transition is identified in the t-t ′ -J model. The orbital-antisymmetric copper-oxygen singlet is confirmed to be irrelevant, as found originally. The usual symmetry analysis is extended to include dynamical symmetries.

show abstract

Electronic pseudogap of optimally doped high-temperatureNd2−xCexCuO4superconductors

Cited by 14 publications

References 27 publications

Approaching Large U d High-T c Cuprates from the Covalent Side

Approaching Large U d High-T c Cuprates from the Covalent Side

Competition between Antiferromagnetism and Superconductivity in the Electron-Doped Cuprates Triggered by Oxygen Reduction

Destabilization of the Zhang-Rice singlet at optimal doping

Contact Info

Product

Resources

About