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Cvitanić, Tonči; Pelc, Damjan; Požek, Miroslav; Amit, Eran; Keren, Amit

doi:10.1103/physrevb.90.054508

Cited by 13 publications

(12 citation statements)

References 39 publications

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“…Above T = 400 K the resistivity bends down (dashed line), signaling a novel conductivity mechanism, probably due to the pseudogap (see Section 5). The pseudogap has been determined from NMR spectra via a characteristic temperature T * and the Knight shift [29]. Due to an odd number of electrons, the Cu(II) sites and surrounding oxygen sites are spin polarized.…”

Section: One-electron Exchange In the Underdoped Casementioning

confidence: 99%

Conductivity in Cuprates Arises from Two Different Sources: One-Electron Exchange and Disproportionation

Larsson

2016

J Supercond Nov Magn

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Simulation of the resistivity in the normal state of doped La 2−x Sr x CuO 4 has been performed using a hopping model based on Marcus theory. The results are in substantial agreement with experimental results. At oxidative doping, Cu(III) sites are formed and electron mobility possible due to hopping: Cu(III)Cu(II) → Cu(II)Cu(III) (one-electron exchange). In the underdoped, non-metallic region, the resistivity (ρ) decreases from almost insulation at T = 0 to a minimum at about T = 100 K. ρ then increases more than linearly with T (∼ T 3/2 ) in the region 100 < T < 500 K. A photo-induced metal-metal (MM) charge transfer transition at 2 eV 2Cu(II) + hν → Cu(I) + Cu(III) is responsible for the strong absorption in the visible spectrum of La 2 CuO 4 . The down-shift of spectral density with doping (x) in La 2−x Sr x CuO 4 depends on the appearance of Cu(III) sites which makes optical as well as thermal one-electron exchange transitions possible with lower energy. Disproportionation occurs spontaneously for x > 0.06, opening up for electron pair formation. Configuration interaction between two-electron states of low chemical potential, but strong vibrational coupling, gives rise to the superconductor and pseudogaps. Data from photo-induced conductivity and absorption spectra are used in the simulation, which gives results in good agreement with experiments. Possible explanations for Raman and MIR absorption suggest themselves.

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Section: One-electron Exchange In the Underdoped Casementioning

confidence: 99%

Conductivity in Cuprates Arises from Two Different Sources: One-Electron Exchange and Disproportionation

Larsson

2016

J Supercond Nov Magn

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“…Therefore, x tunes both J (through a and θ ) and orbital splitting (through d A ) over the whole phase diagram. Moreover, disorder in CLBLCO was found to be x independent based on the linewidths measured by techniques ranging from high-resolution powder x-ray diffraction [22], Cu, Ca, and O nuclear magnetic resonance [23][24][25][26], phonon [27], and angle-resolved photoemission spectroscopy (ARPES) [28]. Intriguingly, both J , as measured in undoped CLBLCO samples, and T [29], which plots the Néel (T N ), spin-glass (T g ), and superconducting (T c ) transition temperatures as a function of the stoichiometric oxygen amount y for various families (x).…”

Section: Introductionmentioning

confidence: 99%

Correlation of the superconducting critical temperature with spin and orbital excitations in(CaxLa1−x)(Ba1.75−
Ellis
¹
,
Huang
²
,
Olalde-Velasco
³

et al. 2015
Phys. Rev. B
31
1
19
1
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Electronic spin and orbital (dd) excitation spectra of (Ca x La 1−x )(Ba 1.75−x La 0.25+x )Cu 3 O y samples are measured by resonant inelastic x-ray scattering (RIXS). In this compound, T c of samples with identical hole dopings is strongly affected by the Ca/Ba substitution x due to subtle variations in the lattice constants, while crystal symmetry and disorder as measured by linewidths are x independent. We examine two extreme values of x and two extreme values of hole-doping content y corresponding to antiferromagnetic and superconducting states. The x dependence of the spin-mode energies is approximately the same for both the antiferromagnetic and superconducting samples. This clearly demonstrates that RIXS is sensitive to the superexchange J even in doped samples. A positive correlation between J and the maximum of T c at optimal doping (T max c ) is observed. We also measured the x dependence of the d xy → d x 2 −y 2 and d xz/yz → d x 2 −y 2 orbital splittings. We infer that the effect of the unresolved d 3z 2 −r 2 → d x 2 →y 2 excitation on T max c is much smaller than the effect of J . There appears to be dispersion in the d xy → d x 2 −y 2 peak of up to 0.05 eV. Our fitting furthermore indicates an asymmetric dispersion for the d xz/yz → d x 2 −y 2 excitation. A peak at ∼0.8 eV is also observed and attributed to a dd excitation in the chain layer.

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“…In contrast, T max c appears to show an anomalous suppression which grows with decreasing x, thereby effectively reversing its correlation with J. The reasons for such a suppression are not apparent and, for example, NMR studies suggest it is not associated with disorder scattering [16][17][18]. These are interesting model systems that deserve more study if systematic behavior is to be elucidated.…”

Section: Discussionmentioning

confidence: 99%

Relevance of magnetism to cuprate superconductivity: Lanthanides versus charge-compensated cuprates

Keren¹,

Crump²,

Mallett³

et al. 2019

Phys. Rev. B

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We address what seemed to be a contradiction between the lanthanide series REBa2Cu3Oy (RE123) and the charge-compensated series (CaxLa1−x)(Ba1.75−xLa0.25+x)Cu3Oy (CLBLCO) regarding the superexchange (J) dependence of the maximum superconductivity (SC) critical temperature T max c (J); RE and x are implicit variables. This is done by measuring the Néel temperature and the temperature dependence of the magnetic order parameter for RE=Nd, Sm, Eu, Gd, Dy, Yb, Y, and for Y(BaSr)Cu3Oy, at various very light dopings. The doping is determined by thermopower, and the magnetic properties by muon spin rotation. We find that the normalized-temperature dependence of the order parameter is identical for all RE123 in the undoped limit (with the exception of Gd123) implying identical out-of-plane magnetic coupling. The extrapolation of TN to zero doping suggests that, despite the variations in ionic radii, J varies too weakly in this system to test the relation between SC and magnetism. This stands in contrast to CLBLCO where both T max c and T max N vary considerably in the undoped limit, and a positive correlation between the two quantities was observed.

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17O-NMRKnight shift study of the interplay between superconductivity and pseudogap in(CaxLa1−x

Cited by 13 publications

References 39 publications

Conductivity in Cuprates Arises from Two Different Sources: One-Electron Exchange and Disproportionation

Conductivity in Cuprates Arises from Two Different Sources: One-Electron Exchange and Disproportionation

Correlation of the superconducting critical temperature with spin and orbital excitations in(CaxLa1−x)(Ba1.75−
Ellis
¹
,
Huang
²
,
Olalde-Velasco
³

et al. 2015
Phys. Rev. B
31
1
19
1
View full text Add to dashboard Cite

Relevance of magnetism to cuprate superconductivity: Lanthanides versus charge-compensated cuprates

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17O-NMRKnight shift study of the interplay between superconductivity and pseudogap in(CaxLa1−x

Cited by 13 publications

References 39 publications

Conductivity in Cuprates Arises from Two Different Sources: One-Electron Exchange and Disproportionation

Conductivity in Cuprates Arises from Two Different Sources: One-Electron Exchange and Disproportionation

Correlation of the superconducting critical temperature with spin and orbital excitations in(CaxLa1−x)(Ba1.75−Ellis1, Huang2, Olalde-Velasco3 et al. 2015Phys. Rev. B311191View full textAdd to dashboardCite

Relevance of magnetism to cuprate superconductivity: Lanthanides versus charge-compensated cuprates

Contact Info

Product

Resources

About

Correlation of the superconducting critical temperature with spin and orbital excitations in(CaxLa1−x)(Ba1.75−
Ellis
¹
,
Huang
²
,
Olalde-Velasco
³

et al. 2015
Phys. Rev. B
31
1
19
1
View full text Add to dashboard Cite