NMR investigation of low energy excitations in high<i>T</i><sub>c</sub>superconductors

Berthier, C.; Gillet, J.A.; Auler, T.; Berthier, Y.; Horvatić, M.; Ségransan, P.; Henry, J.Y.

doi:10.1088/0031-8949/1993/t49a/022

Cited by 20 publications

(7 citation statements)

References 25 publications

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“…In this context, the plateau mentioned above can be a consequence of the slowing down of the quadrupolar fluctuations at a temperature higher than that at which the Cu(1) line broadens. An important feature which emerges from our data is the strongly different behavior of the Cu(1) T-dependence SLRR as compared to that of Cu(2) which presents a well known sudden decrease below T c associated to the opening of the superconducting energy gap in overdoped Y-123 [18]. This rules out a proximity induced superconducting state in the chains just below T c .…”

mentioning

confidence: 58%

In-Plane Charge Modulation belowTcand Charge-Density-Wave Correlations in the Chain Layer inYBa2

Grévin¹,

Berthier²,

Collin

2000

Phys. Rev. Lett.

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Nuclear quadrupole resonance (NQR) measurements have been performed on Cu(2) plane sites and Cu(1) chain sites in fully doped YBa2Cu3O7 between 300 and 4.2 K. The sharp increase of the Cu(1) NQR linewidth across the superconducting transition and the T dependence of the Cu(1) spin lattice relaxation rate confirm the existence of a charge-density-wave state (CDW) in the chains. The simultaneous broadening of the Cu(2) linewidth below T(c) and the anomalous T dependence of Cu(1) and Cu(2) NQR parameters indicate that these in-chain CDW correlations are strongly involved in the appearance of an in-plane charge modulated structure below T(c).

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mentioning

confidence: 58%

In-Plane Charge Modulation belowTcand Charge-Density-Wave Correlations in the Chain Layer inYBa2

Grévin¹,

Berthier²,

Collin

2000

Phys. Rev. Lett.

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“…One of the most important aspect of the experimental results 24,29 is that the oxygen relaxation rate divided by the oxygen Knight shift does not vary either with…”

Section: Nmr and Inelastic Magnetic Neutron Scatteringmentioning

confidence: 99%

Non-Fermi-liquid states and pairing instability of a general model of copper oxide metals

Varma¹

1997

Phys. Rev. B

592

610

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A model of copper-oxygen bonding and anti-bonding bands with the most general two-body interactions allowable by symmetry is considered. The model has a continuous transition as a function of hole-density x and temperature T to a phase in which a current circulates in each unit cell. This phase preserves the translational symmetry of the lattice while breaking time-reversal invariance and the four-fold rotational symmetry. The product of time-reversal and four-fold rotation is preserved. The circulating current phase terminates at a critical point at x = x c , T = 0. In the quantum-critical region about this point the logarithm of the frequency of the current fluctuations scales with their momentum. The microscopic basis for the marginal Fermi-liquid phenemenology and the observed long wavelength transport anomalies near x = x c are derived from such fluctuations. The symmetry of the current fluctuations is such that the associated magnetic field fluctuations are absent at oxygen sites and have the correct form to explain the anomalous copper nuclear relaxation rate. Cross-overs to the Fermi-liquid phase on either side of x c and the role of disorder are briefly considered. The current fluctuations promote superconductive instability with a propensity towards "D-wave" symmetry or "extended S-wave"symmetry depending on details of the band-structure. Several experiments are proposed to test the theory.

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“…This phase is characterized by violation of fundamental Fermi liquid scaling laws, and by its close proximity to other exotic phases such as unconventional superconductivity, charge or spin density waves, and nematicity [1,4,6,8]. For example, the prototypical copper-oxide strange metals, which are also high temperature superconductors, exhibit a resistivity that is linear in temperature and exceeds the Mott-Ioffe-Regel limit [2,9], an optical conductivity exhibiting an anomalous power law dependence on frequency [10,11], a magnetoresistance that is linear in field, violating Kohler's rule [12], a quasiparticle decay rate that scales linearly with energy [13], and an NMR spin relaxation rate that violates the Korringa law [14]. No generally accepted theory of matter can explain these properties, which appear to be incompatible with fundamental assumptions of Boltzmann transport theory.…”

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confidence: 99%

Crossover of Charge Fluctuations across the Strange Metal Phase Diagram

et al. 2019

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A normal metal exhibits a valence plasmon, which is a sound wave in its conduction electron density. The mysterious strange metal is characterized by non-Boltzmann transport and violates most fundamental Fermi liquid scaling laws. A fundamental question is: Do strange metals have plasmons? Using momentum-resolved inelastic electron scattering (M-EELS) we recently showed that, rather than a plasmon, optimally-doped Bi2.1Sr1.9Ca1.0Cu2.0O8+x (Bi-2212) exhibits a featureless, temperature-independent continuum with a power-law form over most energy and momentum scales [M. Mitrano, PNAS 115, 5392-5396 (2018)]. Here, we show that this continuum is present throughout the fan-shaped, strange metal region of the phase diagram. Outside this region, dramatic changes in spectral weight are observed: In underdoped samples, spectral weight up to 0.5 eV is enhanced at low temperature, biasing the system towards a charge order instability. The situation is reversed in the overdoped case, where spectral weight is strongly suppressed at low temperature, increasing quasiparticle coherence in this regime. Optimal doping corresponds to the boundary between these two opposite behaviors at which the response is temperature-independent. Our study suggests that plasmons do not exist as well-defined excitations in Bi-2212, and that a featureless continuum is a defining property of the strange metal, which is connected to a peculiar crossover where the spectral weight change undergoes a sign reversal. arXiv:1903.04038v2 [cond-mat.str-el]

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NMR investigation of low energy excitations in highT_csuperconductors

Cited by 20 publications

References 25 publications

In-Plane Charge Modulation belowTcand Charge-Density-Wave Correlations in the Chain Layer inYBa2

In-Plane Charge Modulation belowTcand Charge-Density-Wave Correlations in the Chain Layer inYBa2

Non-Fermi-liquid states and pairing instability of a general model of copper oxide metals

Crossover of Charge Fluctuations across the Strange Metal Phase Diagram

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NMR investigation of low energy excitations in highTcsuperconductors

Cited by 20 publications

References 25 publications

In-Plane Charge Modulation belowTcand Charge-Density-Wave Correlations in the Chain Layer inYBa2

In-Plane Charge Modulation belowTcand Charge-Density-Wave Correlations in the Chain Layer inYBa2

Non-Fermi-liquid states and pairing instability of a general model of copper oxide metals

Crossover of Charge Fluctuations across the Strange Metal Phase Diagram

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NMR investigation of low energy excitations in highT_csuperconductors