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Kendziora, Christopher A.; Rosenberg, A.

doi:10.1103/physrevb.52.r9867

Cited by 81 publications

(74 citation statements)

References 31 publications

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“…The coherence peak energy remains below 4.2k B T c for the B 1g channel and is even lower for the A 1g channel. The reduced energies for all the channels are lower than for p-doped materials 36,48,49,54 suggesting a d-wave BCS weak coupling limit in the n-doped cuprates for optimally-and over-doped samples.…”

Section: 16mentioning

confidence: 84%

Evolution of superconductivity in electron-doped cuprates: Magneto-Raman spectroscopy

Qazilbash

Koitzsch²,

Dennis³

et al. 2005

Phys. Rev. B

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The electron-doped cuprates Pr2−xCexCuO 4−δ (PCCO) and Nd2−xCexCuO 4−δ (NCCO) have been studied by electronic Raman spectroscopy across the entire region of the superconducting (SC) phase diagram. The SC pairing strength is found to be consistent with a weak-coupling regime except in the under-doped region where we observe an in-gap collective mode at 4.5kB Tc while the maximum amplitude of the SC gap is ≈ 8kBTc. In the normal state, doped carriers divide into coherent quasi-particles (QPs) and carriers that remain incoherent. The coherent QPs mainly reside in the vicinity of (±π/2a, ±π/2a) regions of the Brillouin zone (BZ). We find that only coherent QPs contribute to the superfluid density in the B2g channel. The persistence of SC coherence peaks in the B2g channel for all dopings implies that superconductivity is mainly governed by interactions between the hole-like coherent QPs in the vicinity of (±π/2a, ±π/2a) regions of the BZ. We establish that superconductivity in the electron-doped cuprates occurs primarily due to pairing and condensation of hole-like carriers. We have also studied the excitations across the SC gap by Raman spectroscopy as a function of temperature (T ) and magnetic field (H) for several different cerium dopings (x). Effective upper critical field lines H * c2 (T, x) at which the superfluid stiffness vanishes and H 2∆ c2 (T, x) at which the SC gap amplitude is suppressed by field have been determined; H 2∆ c2 (T, x) is larger than H * c2 (T, x) for all doping concentrations. The difference between the two quantities suggests the presence of phase fluctuations that increase for x < ∼ 0.15. It is found that the magnetic field suppresses the magnitude of the SC gap linearly at surprisingly small fields.

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Section: 16mentioning

confidence: 84%

Evolution of superconductivity in electron-doped cuprates: Magneto-Raman spectroscopy

Qazilbash

Koitzsch²,

Dennis³

et al. 2005

Phys. Rev. B

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“…3(b) shows the magnitude of the combined SC gap and pseudogap, ∆ max , measured from the calculated DOS at 10K. ∆ max increases with decreasing doping just as observed from ARPES [22], tunnelling [23] and Raman scattering [24]. Also plotted is the SC gap magnitude ∆, determined by setting E g = 0 and measuring the gap in the calculated DOS at 10K.…”

mentioning

confidence: 88%

Thermodynamic properties ofBi2Sr2CaCu2O8calculated from the ele

2008

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The electronic dispersion for Bi2Sr2CaCu2O 8+δ has been determined from angle-resolved photoelectron spectroscopy (ARPES). From this dispersion we calculate the entropy and superfluid density. Even with no adjustable parameters we obtain an exceptional match with experimental data across the entire phase diagram, thus indirectly confirming both the ARPES and thermodynamic data. The van Hove singularity is crossed in the overdoped region giving a distinctive linear-in-T temperature dependence in the superfluid density there.PACS numbers: 74.25. Bt, 74.25.Jb, 74.62.Dh, The generic doping dependence of the thermodynamic, electrodynamic and transport properties of high-T c superconductors remains a puzzle despite many years of study. Their unusual behaviour is often taken to be a signature of exotic physics yet it should be related to the electronic energy-momentum dispersion, obtained for example from angle-resolved photoemission spectroscopy (ARPES). These studies indicate the presence of an extended van Hove saddle-point singularity[1] situated at the (0,π) point together with a normal-state pseudogap [2] as common features in the electronic band structure of the cuprate superconductors. The pseudogap exhibits a reduction in the density of states (DOS) at the Fermi level which is believed to develop into a fully nodal gap at low temperature [3].In theories based on the so-called van Hove scenario[4] the superconducting (SC) transition temperature, T c , is enhanced by the close proximity of a van Hove singularity (vHs). These theories assume that the vHs sweeps through the Fermi level at around optimal doping (p = 0.16), indeed causing the peak in T c (p). However, ARPES measurements of the band structure of Bi-2201[5] show that the vHs crosses the Fermi level in the deeply overdoped side of the phase diagram. For a bilayer cuprate like Bi-2212 the weak coupling between the layers splits the bands near the (π, 0) points into an upper antibonding band and a lower bonding band. ARPES measurements performed on Bi-2212 [6] suggest that the antibonding band vHs crosses at around p = 0.225 where T c ≈ 60K i.e. near the limit for overdoping in this material. The vHs crossing should profoundly affect all physical properties.In this work we have used the thermodynamic properties as a window on the electronic structure to independently check the main ARPES results. Using an ARPESderived energy dispersion we have calculated the doping and temperature dependence of the entropy and superfluid density of Bi-2212. All details for our calculations are taken directly, and only, from ARPES in order to determine the implications of this data. Our calculations confirm the ARPES results, giving a consistent picture of the thermodynamic and electrodynamic properties in terms of a proximate vHs.We assume Fermi-liquid-like, mean-field, weakcoupling physics in spite of indications, or expectations, to the contrary. In defense of our approach (i) the thermodynamics at low T is dominated by the nodal regions of the Fermi surface where qua...

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“…Wakimoto et al 55 found the incommensurate spin order also to disappear there. If one examines the B 1g gap maxima on the overdoped side of the phase diagram 28,33,86,[89][90][91] , it becomes clear that the intensity increases beyond p = 0.21, which can hardly be traced back to coherence. Actually, the increase is so fast that a divergence point may be anticipated.…”

Section: Phase Diagrammentioning

confidence: 99%

Electron interactions and charge ordering in CuO 2 compounds

Muschler

Prestel

Tassini

et al. 2010

Eur. Phys. J. Spec. Top.

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We present results of inelastic light scattering experiments on singlecrystalline La2−xSrxCuO4 in the doping range 0.00 ≤ x = p ≤ 0.30 and Tl2Ba2CuO 6+δ at p = 0.20 and p = 0.24. The main emphasis is placed on the response of electronic excitations in the antiferromagnetic phase, in the pseudogap range, in the superconducting state, and in the essentially normal metallic state at x ≥ 0.26, where no superconductivity could be observed. In most of the cases we compare B1g and B2g spectra which project out electronic properties close to (π, 0) and (π/2, π/2), respectively. In the channel of electron-hole excitations we find universal behavior in B2g symmetry as long as the material exhibits superconductivity at low temperature. In contrast, there is a strong doping dependence in B1g symmetry: (i) In the doping range 0.20 ≤ p ≤ 0.25 we observe rapid changes of shape and temperature dependence of the spectra. (ii) In La2−xSrxCuO4 new structures appear for x < 0.13 which are superposed on the electron-hole continuum. The temperature dependence as well as model calculations support an interpretation in terms of charge-ordering fluctuations. For x ≤ 0.05 the response from fluctuations disappears at B1g and appears at B2g symmetry in full agreement with the orientation change of stripes found by neutron scattering. While, with a grain of salt, the particle-hole continuum is universal for all cuprates the response from fluctuating charge order in the range 0.05 ≤ p < 0.16 is so far found only in La2−xSrxCuO4. We conclude that La2−xSrxCuO4 is close to static charge order and, for this reason, may have a suppressed Tc.

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a-bplane anisotropy of the superconducting gap inBi2Sr2

Cited by 81 publications

References 31 publications

Evolution of superconductivity in electron-doped cuprates: Magneto-Raman spectroscopy

Evolution of superconductivity in electron-doped cuprates: Magneto-Raman spectroscopy

Thermodynamic properties ofBi2Sr2CaCu2O8calculated from the ele

Electron interactions and charge ordering in CuO 2 compounds

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