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Wang, N. L.; Tajima, S.; Rykov, Alexandre I.; Tomimoto, K.

doi:10.1103/physrevb.57.r11081

Cited by 48 publications

(45 citation statements)

References 18 publications

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“…The fact that pinned charge density waves are the natural non-quasiparticle collective mode that leads to the response shown in figure 1 has previously been noted in [35]. That paper, as well as [36,37], have furthermore shown that the nonzero frequency peak can be created and pushed to higher frequencies by increased disorder. This is the behavior expected for density waves due to increased pinning.…”

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confidence: 63%

Bad Metals from Fluctuating Density Waves

et al. 2017

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Bad metals have a large resistivity without being strongly disordered. In many bad metals the Drude peak moves away from zero frequency as the resistivity becomes large at increasing temperatures. We catalogue the position and width of the 'displaced Drude peak' in the observed optical conductivity of several families of bad metals, showing that ω peak ∼ ∆ω ∼ k B T /ħ h. This is the same quantum critical timescale that underpins the T -linear dc resistivity of many of these materials. We provide a unified theoretical description of the optical and dc transport properties of bad metals in terms of the hydrodynamics of short range quantum critical fluctuations of incommensurate density wave order. Within hydrodynamics, pinned translational order is essential to obtain the nonzero frequency peak. Check for updates doi:10.21468/SciPostPhys.3.3.025 Bad metals are defined by the fact that if their electrical resistivity is interpreted within a conventional Drude formalism, the corresponding mean free path of the quasiparticles is so short that the Boltzmann equation underlying Drude theory is not consistent [1][2][3]. As such, bad metals pose a long-standing challenge to theory. In this work we show that the hydrodynamics of phase-fluctuating charge density waves can lead to bad metallic behavior. Hydrodynamics is a tightly constrained formalism for the low energy and long wavelength dynamics of media [4,5]. Non-quasiparticle media, in particular, exhibit fast local thermalization leading to extended hydrodynamics regimes. Phase fluctuations in the density wave can be robustly incorporated into this description and will be essential in order for the states to be metallic, rather than insulating. We will use the hydrodynamic framework to explain observed dc and optical transport behavior that is common to several families of bad metal materials.Recent work has emphasized that the absence of quasiparticles is not sufficient to obtain a bad metal [6]. If the total momentum of the charge carriers is long-lived, then the resistivity will be small even if all single-particle excitations decay rapidly. The importance of the fate of momentum for transport has long been appreciated [7,8], but has acquired renewed relevance 1 SciPost Phys. 3, 025 (2017) in the context of modern unconventional metals, e.g. [9,10]. Two previously considered scenarios for removing the long-lived momentum (sound) mode from the collective description of charge transport are as follows. Firstly, that the low energy, non-quasiparticle, description of bad metals is strongly non-translationally invariant and hence momentum is absent from the hydrodynamic description [6]. Secondly, that an emergent particle-hole symmetry at low energies decouples charge transport from momentum [11]. These mechanisms do not seem to be at work in bad metals. The resistivity of bad metals is not typically strongly dependent on the strength of disorder and some bad metals appear to be relatively clean. Emergent particle-hole symmetry does not decouple momentum ...

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confidence: 63%

Bad Metals from Fluctuating Density Waves

et al. 2017

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“…Recent experiments [20][21][22][23][24][25][26] [24,25] and optical conductivity [25,26]. In all these experiments, much better metallic properties have been clearly seen along the direction of the chains (b-axis).…”

Section: ∆ ρ(T) ∝ T (1-∆/t) At High Temperatures T > ∆mentioning

confidence: 98%

“…In all these experiments, much better metallic properties have been clearly seen along the direction of the chains (b-axis). And what is truly remarkable, that this large in-plane anisotropy is strongly suppressed by a small (only 0.4 %) amount of Zn [25], which is known to replace copper, at least for Zn concentrations up to 4 %, only in the CuO 2 planes ! The latter suggests that the ab-anisotropy can not be explained just by assuming the existance of highly conducting CuO-chains.…”

Section: ∆ ρ(T) ∝ T (1-∆/t) At High Temperatures T > ∆mentioning

confidence: 99%

1D quantum transport in the even-chain spin-ladder compound Sr _2.5 Ca _11.5 Cu ₂₄ O ₄₁ and YBa ₂ Cu ₄ O ₈

1999

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The temperature dependence of the resistivity ρ(T) of the novel Sr 2.5 Ca 11.5 Cu 24 O 41 ladder compound under hydrostatic pressure of up to 8 GPa has been explained by assuming that the relevant length scale for electrical transport is given by the magnetic correlation length related to the opening of a spin-gap in a 1D even-chain spin-ladder (1D-SL). The pressure dependence of the gap was extracted by applying this model to ρ(T) data obtained at different pressures. The ρ(T) dependence of the underdoped cuprate YBa 2 Cu 4 O 8 demonstrates a remarkable scaling with the ρ(T) of the 1D-SL compound Sr 2.5 Ca 11.5 Cu 24 O 41 . This scaling implies that underdoped cuprates at T c < T < T * are in the 1D regime and their pseudo-gap below T * is the spin-gap in the even-chain 1D-SL formed at T < T * in these materials. The temperature dependent resistivity ρ(T) of high-T c cuprates has recently been interpreted in the framework of the two-dimensional (2D) Heisenberg model [1]. The approach proposed in Ref. 1 is based on the three basic assumptions: (i) the dominant scattering mechanism in high-T c 's in the whole temperature range is of magnetic origin; (ii) the specific temperature dependence of the resistivity ρ(T) can be described by the inverse quantum conductivity σ -1 with the inelastic length L φ being fully controlled, via a strong interaction of holes with Cu 2+ spins, by the magnetic correlation length ξ m , and, finally, (iii) the proper 2D expressions should be used for calculating the quantum conductivity with L φ~ξm .With a few straightforward modifications, these ideas can also be applied to the 1D quantum spin-ladder (SL) systems [2]. In this case the quantum resistance of a single 1D wire is a linear function of the inelastic length L φ [3] and ρ(T) can be represented asHere b is the diameter of a single 1D wire and L φ~ξm1D is given by the spin-correlation length ξ m1D in the 1D regime. For a quantum 1D transport, the concentration of the

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“…Finally, we comment that we expect impurities to have little effect in c-axis transport, since the states which carry most of the current along the c-axis are those which are most three-dimensional, and therefore are least affected by chain disorder. In a series of conductivity experiments on Zn doped samples, Wang et al 28 have found that while the a-b anisotropy is strongly affected by small amounts of Zn, the c-axis conductivity is almost unchanged.…”

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confidence: 99%

Disorder and chain superconductivity inYBa2Cu3O7
Atkinson¹
1999
Phys. Rev. B
39
4
45
0
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The effects of chain disorder on superconductivity in YBa2Cu3O 7−δ are discussed within the context of a proximity model. Chain disorder causes both pair-breaking and localization. The hybridization of chain and plane wavefunctions reduces the importance of localization, so that the transport anisotropy remains large in the presence of a finite fraction δ of oxygen vacancies. Penetration depth and specific heat measurements probe the pair-breaking effects of chain disorder, and are discussed in detail at the level of the self-consistent T-matrix approximation. Quantitative agreement with these experiments is found when chain disorder is present. 74.25.Ha,74.25.Bt Current understanding of the low energy electronic excitation spectrum of YBa 2 Cu 3 O 7−δ (YBCO) is incomplete. As with other high T c superconductors, YBCO is a layered compound in which the CuO 2 layers are conducting, strongly correlated quasi-two-dimensional electron gasses. 4 Measurements of the penetration depth λ c along the c-axis (perpendicular to the layers) find a power law dependence on temperature which is material dependent. In some cases, such as in-plane anisotropic conductivity measurements, 2 it is straightforward to distinguish the contributions of the chains from those of the planes. In general, however, the influence of the chains is not trivial to understand. Calculations based on multi-band models suggest, for example, that interband transitions between the plane and chain bands dominate the c-axis conductivity, 11 and that the pseudogap seen in optical conductivity experiments reflects a shift in interband transition energies due to the opening of a gap 12 in the CuO 2 -layer Fermi surface. These predictions are quite different from those of one-band models, [13][14][15] in which disorder and inelastic scattering are assumed to play a key role in c-axis transport. For this reason, it is essential to develop a model which correctly describes the low energy physics of the chain-plane system.Evidence concerning the chain electronic structure is indirect. In YBa 2 Cu 3 O 7−δ , the chains are not continuous, but are broken into segments of finite length by the fraction δ of vacant chain oxygen sites. In spite of this, there is a large anisotropy in the in-plane conductivity, 2 indicating that the chains are metallic. The absence of localization suggests that electronic states associated with the chains, while highly anisotropic, are not onedimensional. In the superconducting state, the in-plane anisotropy 16 in the penetration depth λ is nearly identical in magnitude to the conductivity anisotropy, suggesting a significant superfluid density on the chain layer for temperatures T ≪ T c . What is truly remarkable, however, is that the temperature dependence of the chain superfluid density-as measured in penetration depth experiments 17 -is almost the same as that of the planes. The apparent similarity of the excitation spectra in the chain and plane layers is surprising given that the underlying bands have completely different struc...

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Zn-substitution effects on the optical conductivity inYBa2Cu3O

Cited by 48 publications

References 18 publications

Bad Metals from Fluctuating Density Waves

Bad Metals from Fluctuating Density Waves

1D quantum transport in the even-chain spin-ladder compound Sr _2.5 Ca _11.5 Cu ₂₄ O ₄₁ and YBa ₂ Cu ₄ O ₈

Disorder and chain superconductivity inYBa2Cu3O7
Atkinson¹
1999
Phys. Rev. B
39
4
45
0
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Zn-substitution effects on the optical conductivity inYBa2Cu3O

Cited by 48 publications

References 18 publications

Bad Metals from Fluctuating Density Waves

Bad Metals from Fluctuating Density Waves

1D quantum transport in the even-chain spin-ladder compound Sr 2.5 Ca 11.5 Cu 24 O 41 and YBa 2 Cu 4 O 8

Disorder and chain superconductivity inYBa2Cu3O7Atkinson1 1999Phys. Rev. B394450View full textAdd to dashboardCite

Contact Info

Product

Resources

About

1D quantum transport in the even-chain spin-ladder compound Sr _2.5 Ca _11.5 Cu ₂₄ O ₄₁ and YBa ₂ Cu ₄ O ₈

Disorder and chain superconductivity inYBa2Cu3O7
Atkinson¹
1999
Phys. Rev. B
39
4
45
0
View full text Add to dashboard Cite