Planar Cu and O hole densities in high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>cuprates determined with NMR

Haase, Jürgen; Sushkov, O. P.; Horsch, Peter; Williams, G. V. M.

doi:10.1103/physrevb.69.094504

Cited by 82 publications

(133 citation statements)

References 40 publications

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“…2c). The validity of this assumption is supported by a recent analysis of NMR and atomic spectroscopic results indicating that the doped holes reside almost exclusively on the planar oxygen, and that the EFG is linearly proportional to n p [21]. As seen in Fig.…”

supporting

confidence: 64%

“…However, the planar oxygen does not suffer the same fate: it experiences an isotropic transferred hyperfine coupling (129 kOe/µ B ) to the two nearest neighbor Cu spins, so for antiferromagnetically correlated neighbors, the hyperfine field at the O site vanishes [20]. Furthermore, 17 O (I=5/2) has a quadrupolar moment ( 17 Q = -2.56 ×10 −26 cm 2 ), so it is sensitive to the EFG at the nuclear site, which is a measure of the local hole doping [21]. Although previous NMR studies have shown the presence of spatial modulations due to doping inhomogeneities in superconducting La 2−x Sr x CuO 4 [6,8], O NMR in La 1.8−x Eu 0.2 Sr x CuO 4 provides a unique opportunity to investigate the doping inhomogeneity in a system where the spin fluctuations are suppressed.…”

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confidence: 99%

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Nuclear-Magnetic-Resonance Evidence for Charge Inhomogeneity in Stripe OrderedLa1.8−xEu0.2SrxCuO4

et al. 2006

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We report 17 O Nuclear Magnetic Resonance (NMR) results in the stripe ordered La1.8−xEu0.2SrxCuO4 system. Below a temperature Tq ∼ 80K, the local electric field gradient (EFG) and the absolute intensity of the NMR signal of the planar O site exhibit a dramatic decrease. We interpret these results as microscopic evidence for a spatially inhomogeneous charge distribution, where the NMR signal from O sites in the domain walls of the spin density modulation are wiped out due to large hyperfine fields, and the remaining signal arises from the intervening Mott insulating regions.PACS numbers: 74.72. Dn, 75.10.Nr, Several doped transition metal oxides exhibit inhomogeneous charge stripe order on a mesoscopic scale due to competing long and short range interactions acting on the charge carriers [1,2]. In the cuprates, the doped charge carriers (holes) are expected to form one-dimensional channels (charge stripes) separating regions of insulating antiferromagnetic order of the Cu spins (spin stripes) [3]. The presence of this inhomogeneity may be vital to the mechanism of d-wave superconductivity [4], however direct experimental evidence for such structures has been elusive. To date, the only observations have been via techniques that probe either the spin density or the charge inhomogeneity: Neutron Scattering (NS) experiments provided the first evidence for the modulation of spin density that is expected in a stripe lattice [5], whereas NMR and Scanning Tunnelling Microscopy (STM) experiments indicate the presence of inhomogeneous doping distributions [6,7,8,9,10]. In this Letter we discuss new NMR data that provide direct evidence for a correlation between the local charge and spin density maps by taking advantage of the unique properties of the planar oxygen to probe simultaneously both the local spin structure as well as the local hole doping in the O p-orbitals. Our data reveal that not only is the charge spatially inhomogeneous, but that the regions of excess charge are correlated with the domain walls of the spin order, exactly as expected for a stripe pattern [3,11].The rare-earth co-doped La 1.8−x Eu 0.2 Sr x CuO 4 series is ideal for NMR investigations of the spin and charge inhomogeneity. Structurally, this material is almost identical to the prototypical high temperature superconductor La 2−x Sr x CuO 4 , but undergoes a subtle phase transition to the low temperature tetragonal (LTT) structure below T LT = 135K [12]. Instead of superconducting below T c ∼ 35K, this system exhibits glassy magnetic order below T N ∼ 25K [12,13,14,15,16,17,18], and elastic NS measurements have identified static long-range spin and structural modulations that are likely produced by stripe order [5]. The slow spin fluctuations in this system dominate the NMR response of the La and Cu nuclei [14,16,19]. However, the planar oxygen does not suffer the same fate: it experiences an isotropic transferred hyperfine coupling (129 kOe/µ B ) to the two nearest neighbor Cu spins, so for antiferromagnetically correlated neighbors, the hyperf...

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supporting

confidence: 64%

mentioning

confidence: 99%

Nuclear-Magnetic-Resonance Evidence for Charge Inhomogeneity in Stripe OrderedLa1.8−xEu0.2SrxCuO4

et al. 2006

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“…Signal intensity issues have not been properly addressed with most experiments adding to uncertainties. Perhaps the strongest evidence, however, that the observed NMR signals do represent the bulk properties is the fact that the quadrupole splittings measured with NMR account for the average chemical doping [32][33][34].…”

Section: Frequencies Shifts and Splittingsmentioning

confidence: 99%

Contrasting Phenomenology of NMR Shifts in Cuprate Superconductors

2017

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Nuclear magnetic resonance (NMR) shifts, if stripped of their uncertainties, must hold key information about the electronic fluid in the cuprates. The early shift interpretation that favored a single-fluid scenario will be reviewed, as well as recent experiments that reported its failure. Thereafter, based on literature shift data for planar Cu, a contrasting shift phenomenology for cuprate superconductors is developed, which is very different from the early view while being in agreement with all published data. For example, it will be shown that the hyperfine scenario used up to now is inadequate as a large isotropic shift component is discovered. Furthermore, the changes of the temperature dependences of the shifts above and below the superconducting transitions temperature proceed according to a few rules that were not discussed before. It appears that there can be substantial spin shift at the lowest temperature if the magnetic field is perpendicular to the CuO 2 plane, which points to a localization of spin in the 3d(x 2 − y 2 ) orbital. A simple model is presented based on the most fundamental findings. The analysis must have new consequences for theory of the cuprates.

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“…The distribution of local EFGs is directly related to the hole occupation in the O 2p orbitals via the relation ν αα = ν 0 αα + q α n p , where ν 0 αα are material dependent constants, q α = 1.225 MHz for α = (a, c), and 2.452 MHz for α = b, and n p is the hole concentration in the O 2p orbital. 34 Assuming the holes go exclusively into each of these two orbitals, n p = p/2 = 0.105. For a distribution δn p of local hole doping, the quadrupolar contribution to the linewidth would be σ Q = nq α δn p , where n is the particular satellite transition.…”

Section: B Evidence For Electronic Inhomogeneitymentioning

confidence: 99%

“…The dominant contribution arises from this on-site term, and is a direct measure of the doping in the cuprates, which enables us to quantitatively extract the local hole concentration in the oxygen orbitals. 17,34 Susceptibility and resistivity measurements indicate T c = 82 K corresponding to a doping level of p ≈ 0.21. 35 The temperature dependence of the shift, EFG and linewidths were determined by measuring the centers of gravity and second moments n = ±1 satellite transitions.…”

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confidence: 99%

NMR studies of pseudogap and electronic inhomogeneity in Bi2Sr2CaCu2O
Crocker
¹
,
Dioguardi
²
,
apRoberts-Warren
³

et al. 2011
Phys. Rev. B

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We report 17 O NMR measurements in single crystals of overdoped Bi2Sr2CaCu2O 8+δ with Tc = 82 K. We measure the full anisotropy of the planar oxygen Knight shift, electric field gradient, and spin lattice relaxation rate tensors, and show that the entire temperature dependence is determined by the suppression of the density of states in the pseudogap below T * ∼ 94 K. The linewidth can be explained by a combination of magnetic and quadrupolar broadening as a result of an inhomogeneous distribution of local hole concentrations that is consistent with scanning tunneling microscopy measurements. This distribution is temperature independent, does not break C4 symmetry, and exhibits no change below T * or Tc.

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Planar Cu and O hole densities in high-Tccuprates determined with NMR

Cited by 82 publications

References 40 publications

Nuclear-Magnetic-Resonance Evidence for Charge Inhomogeneity in Stripe OrderedLa1.8−xEu0.2SrxCuO4

Nuclear-Magnetic-Resonance Evidence for Charge Inhomogeneity in Stripe OrderedLa1.8−xEu0.2SrxCuO4

Contrasting Phenomenology of NMR Shifts in Cuprate Superconductors

NMR studies of pseudogap and electronic inhomogeneity in Bi2Sr2CaCu2O
Crocker
¹
,
Dioguardi
²
,
apRoberts-Warren
³

et al. 2011
Phys. Rev. B

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Planar Cu and O hole densities in high-Tccuprates determined with NMR

Cited by 82 publications

References 40 publications

Nuclear-Magnetic-Resonance Evidence for Charge Inhomogeneity in Stripe OrderedLa1.8−xEu0.2SrxCuO4

Nuclear-Magnetic-Resonance Evidence for Charge Inhomogeneity in Stripe OrderedLa1.8−xEu0.2SrxCuO4

Contrasting Phenomenology of NMR Shifts in Cuprate Superconductors

NMR studies of pseudogap and electronic inhomogeneity in Bi2Sr2CaCu2OCrocker1, Dioguardi2, apRoberts-Warren3 et al. 2011Phys. Rev. B

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NMR studies of pseudogap and electronic inhomogeneity in Bi2Sr2CaCu2O
Crocker
¹
,
Dioguardi
²
,
apRoberts-Warren
³

et al. 2011
Phys. Rev. B