Temperature-Independent Cuprate Pseudogap from Planar Oxygen NMR

Nachtigal, Jakob; Avramovska, Marija; Erb, A.; Pavićević, Danica; Guehne, Robin; Haase, Jürgen

doi:10.3390/condmat5040066

Cited by 16 publications

(44 citation statements)

References 82 publications

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“…The planar O data, at all doping levels, are in agreement with a single spin component from a metallic density of states with a temperature independent pseudogap at the Fermi surface. The experimentally determined orbital shifts and hyperfine coefficients are in accordance with first principles calculations [6,7,15,16]. Despite this convincing, simple picture, we should point out that there is scatter between different systems above as well as below T c , cf.…”

Section: Discussion Of Cu and O Shiftssupporting

confidence: 83%

“…The pseudogap opens as doping decreases from high levels and can be measured with NMR. The density of states outside the gap or in its absence is universal to the cuprates, independent of doping and family [6]. This scenario is similar to what was concluded from specific heat data [8,9].…”

Section: Introductionsupporting

confidence: 86%

“…Two very recent publications [6,7] revealed that all planar oxygen NMR relaxation and shift data available from the literature for hole-doped cuprates (more than 60 independent data sets in total) are in agreement with a simple metallic spin susceptibility from a density of states that has a temperature independent pseudogap at the Fermi surface. The pseudogap opens as doping decreases from high levels and can be measured with NMR.…”

Section: Introductionmentioning

confidence: 89%

“…The vertical axis was adjusted in offset and scale so that the temperature dependences fill about the same space. These are representative data sets of the recently given full accounts [6,11]. The star (*) denotes samples where 63 Cu and 17 O data had to be taken from different publications and samples (slightly different T c were reported); an underlined legend entry highlights a material (from [11]) for which oxygen data are available.…”

Section: Overviewmentioning

confidence: 99%

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Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

et al. 2022

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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.

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Section: Discussion Of Cu and O Shiftssupporting

confidence: 83%

Section: Introductionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 89%

Section: Overviewmentioning

confidence: 99%

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Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

et al. 2022

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“…The small upturn in S ( T ) near 400 K simply represents the limitations of the present differential technique at such a high temperature and is not seen in the data. We conclude that the pseudogap does not close at some postulated in the range 150–200 K but remains open to the highest temperature investigated—400 K. A similar conclusion has recently been drawn from planar oxygen NMR relaxation data for a number of cuprates 41 . We showed the same long ago 3 for the in-plane resistivity and similarly for the c -axis resistivity 4 , 42 .…”

Section: High-temperature Susceptibility and Entropysupporting

confidence: 78%

Field-dependent specific heat of the canonical underdoped cuprate superconductor $$\hbox {YBa}_2\hbox {Cu}_4\hbox {O}_8$$

Tallon

Loram

2020

Sci Rep

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The cuprate superconductor $$\hbox {YBa}_2\hbox {Cu}_4\hbox {O}_8$$ YBa 2 Cu 4 O 8 , in comparison with most other cuprates, has a stable stoichiometry, is largely free of defects and may be regarded as the canonical underdoped cuprate, displaying marked pseudogap behaviour and an associated distinct weakening of superconducting properties. This cuprate ‘pseudogap’ manifests as a partial gap in the electronic density of states at the Fermi level and is observed in most spectroscopic properties. After several decades of intensive study it is widely believed that the pseudogap closes, mean-field like, near a characteristic temperature, $$T^*$$ T ∗ , which rises with decreasing hole concentration, p. Here, we report extensive field-dependent electronic specific heat studies on $$\hbox {YBa}_2\hbox {Cu}_4\hbox {O}_8$$ YBa 2 Cu 4 O 8 up to an unprecedented 400 K and show unequivocally that the pseudogap never closes, remaining open to at least 400 K where $$T^*$$ T ∗ is typically presumed to be about 150 K. We show from the NMR Knight shift and the electronic entropy that the Wilson ratio is numerically consistent with a weakly-interacting Fermion system for the near-nodal states. And, from the field-dependent specific heat, we characterise the impact of fluctuations and impurity scattering on the thermodynamic properties.

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

Avramovska

Nachtigal

Haase

2022

J Supercond Nov Magn

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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.

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Temperature-Independent Cuprate Pseudogap from Planar Oxygen NMR

Cited by 16 publications

References 82 publications

Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

Planar Cu and O NMR and the Pseudogap of Cuprate Superconductors

Field-dependent specific heat of the canonical underdoped cuprate superconductor $$\hbox {YBa}_2\hbox {Cu}_4\hbox {O}_8$$

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

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