NMR Shift and Relaxation and the Electronic Spin of Superconducting Cuprates

Avramovska, Marija; Pavićević, Danica; Haase, Jürgen

doi:10.1007/s10948-020-05498-y

Cited by 8 publications

(25 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We pointed to the main facts about the Cu and O relaxation above, details have been published [6,12,13,20]. The planar O relaxation of all cuprates follows from a density of states that is common to all cuprates and a doping dependent gap, the relaxation anisotropy is in agreement with the simple hyperfine scenario (5) as well.…”

Section: Planar Cu and O Nuclear Relaxationsupporting

confidence: 55%

“…The density of states outside the gap is common to all cuprates (independent on the size of the gap) and gives a metallic shift from the Korringa relation that is indeed observed. This raised the question of how this spin susceptibility relates to the phenomenology of the planar Cu data that had been published previously [11][12][13]20]. By comparing both sets of data, we conclude that the planar Cu shifts are dominated by the same pseudogap; in particular, the earlier postulated suppression of the planar Cu shifts is a result of this pseudogap [12].…”

Section: Discussionmentioning

confidence: 59%

“…The observation of a doping and family independent metallic planar Cu relaxation that does not show a pseudogap at all is still striking [12,13]. One would argue that this must be related to the metallic density of states observed for planar O, perhaps as a result of antiferromagnetic coupling of the planar Cu spins, as argued before [20].…”

Section: Discussionmentioning

confidence: 80%

“…Thus, (a + c) grows more negative as the temperature is lowered, quite different from (b + c) that vanishes at low temperatures. Some of us argued before [12,20] about plausible assumptions with regard to ( 16) and ( 17): κ 2 = 1 would result from a variation of b only, and a large slope (κ 1 ) results if 4B/(A + 4B) is large. A variation of a only would result in a very small slope, observed for just one system at very low temperatures, cf.…”

Section: Discussion Of Cu and O Shiftsmentioning

confidence: 99%

“…A model for the planar Cu relaxation was discussed recently [20] assuming two spin components α and β that contribute to the fluctuating field at the Cu nucleus (A ,⊥ • α and 4B • β with A = −4B and f = |A ⊥ /A |). It was found that, if both components are fully correlated, α • β = +1 and β • β = +1, one can fit the planar Cu relaxation data and its anisotropy by varying 4β/α from about 0.2 to 0.4.…”

Section: Planar Cu and O Nuclear Relaxationmentioning

confidence: 99%

See 4 more Smart Citations

Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

et al. 2022

Self Cite

View full text Add to dashboard Cite

Recently, an analysis of all available planar oxygen shift and relaxation data for the cuprate high-temperature superconductors showed that the data can be understood with a simple spin susceptibility from a metallic density of states common to all cuprates. It carries a doping dependent but temperature independent pseudogap at the Fermi surface, which causes the deviations from normal metallic behavior, also in the specific heat. Here, a more coherent, unbiased assessment of all data, including planar Cu, is presented and consequences are discussed, since the planar Cu data were collected and analyzed prior to the O data. The main finding is that the planar Cu shifts for one direction of the external magnetic field largely follow from the same states and pseudogap. This explains the shift suppression stated more recently, which leads to the failure of the Korringa relation in contrast to an enhancement of the relaxation due to antiferromagnetic spin fluctuations originally proposed. However, there is still the need for a second spin component that appears to be associated with the Cu 3d(x2−y2) hole to explain the complex Cu shift anisotropy and family dependence. Furthermore, it is argued that the planar Cu relaxation which was reported recently to be rather ubiquitous for the cuprates, must be related to this universal density of states and the second spin component, while not being affected by the simple pseudogap. Thus, while this universal metallic density of states with a pseudogap is also found in the planar Cu data, there is still need for a more elaborate scenario that eludes planar O.

show abstract

Section: Planar Cu and O Nuclear Relaxationsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 59%

Section: Discussionmentioning

confidence: 80%

Section: Discussion Of Cu and O Shiftsmentioning

confidence: 99%

Section: Planar Cu and O Nuclear Relaxationmentioning

confidence: 99%

See 3 more Smart Citations

Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

$$^{17}$$O and $$^{89}$$Y NMR Shift and Relaxation and the Temperature-Independent Pseudogap of the Cuprates

Avramovska

Nachtigal

Haase

2022

J Supercond Nov Magn

View full text Add to dashboard Cite

Nuclear magnetic resonance (NMR) is a powerful local quantum probe of the electronic structure of materials, but in the absence of reliable theory the interpretation of the NMR data can be challenging. This is true in particular for the cuprate high-temperature superconductors. Over the years, a large base of NMR data became available, which makes a review of early assumptions possible. Very recently, it was shown that all planar $$^{17}$$ 17 O NMR shift and relaxation data available in the literature point to a temperature-independent but doping-dependent pseudogap, very similar to what was proposed from the electronic entropy. Here we analyze shift and relaxation of planar O to see whether it follows the very anisotropic and temperature-dependent Cu shift scenario. We find that the O data show a simple, temperature-independent anisotropy in agreement with hyperfine coefficients and orbital shifts predicted by first principles. Furthermore, we show that the original $$^{89}$$ 89 Y shift and relaxation data are in agreement with the proposed temperature-independent pseudogap. This pseudogap depends on doping, but also on the family of materials, and the density of states outside or in the absence of the gap is universal for the cuprates; this suggests that the entropy should be similar for all cuprates, as well. Further consequences will be discussed.

show abstract

A Different NMR View of Cuprate Superconductors

Haase

2022

J Supercond Nov Magn

Self Cite

View full text Add to dashboard Cite

Nuclear magnetic resonance (NMR) is a powerful quantum probe, but the early conclusions on the physics of the cuprates, based on a limited set of data, have to be revised in view of recent findings and results from extensive literature analyses of most NMR data. These show two coupled electronic spin components that influence the nuclei, most easily seen with the planar Cu shift anisotropy. One component is spin from the recently identified ubiquitous metallic excitations, the other likely due to the intrinsic, antiferromagnetically coupled electronic Cu spin. Both components and its intricate interaction leave their imprint on nuclear shifts and relaxation. They also show a family dependence seen in the charge sharing between planar Cu and O. The main phenomena of the doping and temperature dependences of the interplay between both spins components are discussed in terms of an apparent phenomenology that awaits explanation from theory.

show abstract

NMR Shift and Relaxation and the Electronic Spin of Superconducting Cuprates

Cited by 8 publications

References 30 publications

Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

$$^{17}$$O and $$^{89}$$Y NMR Shift and Relaxation and the Temperature-Independent Pseudogap of the Cuprates

A Different NMR View of Cuprate Superconductors

Contact Info

Product

Resources

About