(Sr1−Ca )3Ru2O7 system: optical and ARPES results

Puchkov, A. V.; Schabel, Matthias C.; Basov, D. N.; Startseva, T.; Cao, G.; Timusk, T.; Shen, Zexiang

doi:10.1016/s0022-3697(98)00146-2

Cited by 6 publications

(13 citation statements)

References 12 publications

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“…We show that this propagating spin mode changes the onset frequency for single particle scattering, gives rise to the "peak-dip-hump" features in the quasiparticle spectral function, the "dippeak" features in tunneling SIS and SIN conductances, and to singularities and fine structures in the optical conductivity. In section 6, we apply these results to cuprate superconductors and argue that (i) these features have been observed 147 158,160 are consistent with each other, and (iii) the value of ∆ s extracted from these various experiments coincides with the resonance frequency measured directly in neutron scattering experiments [161][162][163] .…”

Section: Fingerprints Of Spin Fermion Pairingsupporting

confidence: 55%

“…This adjustment yields ω pl ∼ 20000cm −1 . This value is somewhat larger than ω pl ∼ 16000cm obtained experimentally by integrating σ 1 up to about 2 − 2.5eV 158,190,191 , however it agrees with the theoretical result 109 that the sum rule for σ 1 (ω) is exhausted only at extremely high frequencies of about 50ω, that are much larger than 2eV. We see that theoretical calculations of σ 1 (ω) and σ 2 (ω) capture the essential features of the measured forms of the conductivities.…”

Section: The Optical Conductivitymentioning

confidence: 57%

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A Spin Fluctuation Model for d-Wave Superconductivity

Chubukov¹,

Pines²,

Schmalian³

2003

The Physics of Superconductors

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We review the results of the spin-fermion model for correlated electron materials that are sufficiently close to an antiferromagnatic instability that their staggered static magnetic susceptibility in the normal state is large compared to that found in a conventional Fermi liquid. We demonstrate that for such materials magnetically-mediated superconductivity, brought about by the exchange of spin fluctuations, is a viable alternative to conventional phonon-mediated pairing, and leads to pairing in the d x 2 −y 2 channel. If the dominant interaction between quasiparticles is of electronic origin and, at energies much smaller than the fermionic bandwidth, can be viewed as being due to the emission and absorption of a collective, soft spin degree of freedom, the low-energy physics of these materials is accurately described by the spin-fermion model. The derived dynamic magnetic susceptibility and quasiparticle interaction coincide with the the phenomenonological forms used to fit NMR experiments and in earlier Eliashberg calculations. In discussing normal state properties, the pairing instability and superconducting properties, we focus our attention on those materials that, like the cuprate, organic, and some heavy electron superconductors, display quasi-two dimensional behavior. In the absence of superconductivity, at sufficiently low temperatures and energies, a nearly antiferromagnetic Fermi liquid is unconventional, in that the characteristic energy above which a Landau Fermi liquid description is no longer valid is not the Fermi energy, but is the much smaller spin-fluctuation energy,ω sf . For energies (or temperatures) between ω sf and the Fermi energy, the system behavior is quite different from that in a conventional Fermi liquid. Importantly, it is universal in that it is governed by just two input parameters -an effective spin-fermion interaction energy that sets the overall energy scale, and a dimensionless spin-fermion coupling constant that diverges at the antiferromagnetic quantum critical point. We discuss the pairing instability cased by the spin-fluctuation exchange, and "fingerprints" of a spin mediated pairing that are chiefly associated with the emergence of the resonance peak in the spin response of a d-wave superconductor. We identify these fingerprints in spectroscopic experiments on cuprateb superconconductors. We conclude with a discussion of open questions associated primarily with the nature of the pseudogap state found in underdoped cuprates.

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Section: Fingerprints Of Spin Fermion Pairingsupporting

confidence: 55%

Section: The Optical Conductivitymentioning

confidence: 57%

A Spin Fluctuation Model for d-Wave Superconductivity

Chubukov¹,

Pines²,

Schmalian³

2003

The Physics of Superconductors

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“…In Fig. 1͑b͒ we compare our results for 1 () ͑ignoring the contributions from the nodes͒ directly with the experimental data by Puchkov et al 19 for optimally doped YBa 2 Cu 3 O 6ϩ␦ . We used p ϭ1.6ϫ10 4 cm Ϫ1 , similar to that in Ref.…”

Section: Rapid Communicationsmentioning

confidence: 75%

Singularities in the optical response of cuprates

2001

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We argue that the detailed analysis of the optical response in cuprate superconductors allows one to verify the magnetic scenario of superconductivity in cuprates, as for strong coupling charge carriers to antiferromagnetic spin fluctuations, the second derivative of optical conductivity should contain detectable singularities at $2\Delta +\Delta_{\rm spin}$, $4\Delta$, and $2\Delta+2\Delta_{\rm spin}$, where $\Delta$ is the amplitude of the superconducting gap, and $\Delta_{s}$ is the resonance energy of spin fluctuations measured in neutron scattering. We argue that there is a good chance that these singularities have already been detected in the experiments on optimally doped $YBCO$.Comment: 6 pages, 4 figure

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“…46 Consequently, the current-imbalance factor is reduced to 10) where ± corresponds to forward/2k F scattering. The combination of the four Z factors form a scaling function of δk, δp, and δq.…”

Section: √ωmentioning

confidence: 99%

“…observed in the cuprates. 10 The scale Ω min ∼ḡ 2 /E F is parametrically smaller than the scale of the superconducting T c ∼ḡ, hence 1/Ω 1/3 behavior is likely to be masked by superconductivity (or finite T > T c ).…”

Section: /3mentioning

confidence: 99%

Optical conductivity of a two-dimensional metal at the onset of spin-density-wave order

2014

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We consider the optical conductivity of a clean two-dimensional metal near a quantum spindensity-wave transition. Critical magnetic fluctuations are known to destroy fermionic coherence at "hot spots" of the Fermi surface but coherent quasiparticles survive in the rest of the Fermi surface. A large part of the Fermi surface is not really "cold" but rather "lukewarm" in a sense that coherent quasiparticles in that part survive but are strongly renormalized compared to the non-interacting case. We discuss the self-energy of lukewarm fermions and their contribution to the optical conductivity, σ(Ω), focusing specifically on scattering off composite bosons made of two critical magnetic fluctuations. Recent study [S.A. Hartnoll et al., Phys. Rev. B 84, 125115 (2011)] found that composite scattering gives the strongest contribution to the self-energy of lukewarm fermions and suggested that this may give rise to a nonFermi liquid behavior of the optical conductivity at the lowest frequencies. We show that the most singular term in the conductivity coming from self-energy insertions into the conductivity bubble, σ (Ω) ∝ ln 3 Ω/Ω 1/3 , is canceled out by the vertex-correction and Aslamazov-Larkin diagrams. However, the cancelation does not hold beyond logarithmic accuracy, and the remaining conductivity still diverges as 1/Ω 1/3 . We further argue that the 1/Ω 1/3 behavior holds only at asymptotically low frequencies, well inside the frequency range affected by superconductivity. At larger Ω, up to frequencies above the Fermi energy, σ (Ω) scales as 1/Ω, which is reminiscent of the behavior observed in the superconducting cuprates.

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(Sr1−Ca )3Ru2O7 system: optical and ARPES results

Cited by 6 publications

References 12 publications

A Spin Fluctuation Model for d-Wave Superconductivity

A Spin Fluctuation Model for d-Wave Superconductivity

Singularities in the optical response of cuprates

Optical conductivity of a two-dimensional metal at the onset of spin-density-wave order

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