Renormalization of thermal conductivity of disordered d-wave superconductors by impurity-induced local moments

Andersen, Brian M.; Hirschfeld, P. J.

doi:10.1016/j.physc.2007.03.364

Cited by 10 publications

(12 citation statements)

References 11 publications

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“…For YBCO such effects are absent since the disorder potential in the CuO 2 planes is negligible and independent of doping. This result agrees with a recently proposed origin of the unusual transport measurements in LSCO compared to YBCO [19,20].…”

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confidence: 93%

Disorder-Induced Static Antiferromagnetism in Cuprate Superconductors

et al. 2007

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Using model calculations of a disordered d-wave superconductor with on-site Hubbard repulsion, we show how dopant disorder can stabilize novel states with antiferromagnetic order. We find that the critical strength of correlations or impurity potential necessary to create an ordered magnetic state in the presence of finite disorder is reduced compared to that required to create a single isolated magnetic droplet. This may explain why in cuprates like La2−xSrxCuO4(LSCO) low-energy probes have identified a static magnetic component which persists well into the superconducting state, whereas in cleaner systems like YBa2Cu3O 6+δ (YBCO) it is absent or minimal.PACS numbers: 74.25.Jb,74.25.Hc The occurrence of high-temperature superconductivity in cuprates near the antiferromagnetic (AF) phase of the parent compounds has prompted speculation since their discovery that superconductivity and magnetism were intimately related. For the most part, it has been assumed that the two forms of order compete and do not coexist, consistent with the vanishing of the Néel temperature T N before the onset of a superconducting critical temperature T c , and the suppression of T c near doping x = 1/8 where static stripe phases can be stable [1]. On the other hand, there have been persistent reports of static AF at low temperatures T in the superconducting phase at low doping, as measured by muon spin resonance (µSR) [2,3], nuclear magnetic resonance (NMR) [4,5], and elastic neutron scattering (NS) [6,7]. The NS experiments reveal an incommensurate (IC) ordering wavevector evident by a quartet of peaks surrounding (π, π). Since the neutron response is enhanced by an applied magnetic field [6,8,9] several authors have discussed it in terms of coexisting d-wave superconductivity (dSC) and field-induced spin density waves [10]. Recent magnetic Raman scattering data on LSCO has been discussed in terms of such effects as well [11]. However, static order also exists at zero field in the underdoped phase of LSCO [6,7], and has been attributed to disorder [6]. In optimally doped LSCO, Kimura et al. [12] did not detect ordered moments in pure and 1% Zn-substituted samples. An elastic peak similar to the pure underdoped material was observed when 1.7% Zn was added, however [12].Phenomena similar to those in LSCO have been observed in other materials, e.g. Y 1−x Ca x Ba 2 Cu 3 O 6 , and Bi 2 Sr 2 CaCu 2 O 8+x (BSCCO) where µSR directly reveals a slowing down and subsequent freezing of spin fluctuations as T is lowered [2,13]. On the other hand, experiments on optimally doped YBCO, even with significant percentages of Zn, have never detected static magnetic signals. While there have been reports of AF coexisting with dSC in underdoped YBCO, recent NS measurements on YBCO 6.5 found that AF order, while static from the point of view of NS timescales, 10 −10 s, was fluctuating faster than the timescale, 10 −6 s, for µSR. Thus, it appears that while in YBCO low-frequency AF fluctuations are present, they do not "freeze out". Recently, reports of st...

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confidence: 93%

Disorder-Induced Static Antiferromagnetism in Cuprate Superconductors

et al. 2007

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“…Other recent studies relevant to this phase have examined the more disordered, or more correlated state where such magnetic droplets are spontaneously formed around defects in zero field, and shown that they can indeed affect macroscopic observables such as NMR, thermal conductivity and superfluid density ͑T͒. [44][45][46][47][48][49] The physical picture of the ground state, that of an inhomogeneous mixture of AF droplets carrying net moments near the defect, is quite similar in our case. By working in the regime where moments are smaller and the effect of the field is larger, however, we hope to explain some of the observed puzzling aspects of the magnetoresistance.…”

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confidence: 59%

Theory of resistivity upturns in metallic cuprates

2009

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We propose that the experimentally observed resistivity upturn of cuprates at low temperatures may be explained by properly accounting for the effects of disorder in a strongly correlated metallic host. Within a calculation of the dc conductivity using real-space diagonalization of a Hubbard model treated in an inhomogeneous unrestricted Hartree-Fock approximation, we find that correlations induce magnetic droplets around impurities, and give rise to additional magnetic scattering which causes the resistivity upturn. A pseudogap in the density of states is shown to enhance both the disorder-induced magnetic state and the resistivity upturns.

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“…Here, we investigate the effects on κ(T ) by local impurity-induced moments relevant e.g. to the underdoped regime of La 2−x Sr x CuO 4 (LSCO) [11,12,13]. Such moments are formed in the presence of background Hubbard interactions in the host material [14].…”

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confidence: 99%

“…For d-wave superconductors, a real-space BdG calculation of κ(T ) was used to study both localization phenomena [9,13] and the vortex state [30]. Here we follow the same approach but focus on the correlation effects and the role of disorder-induced magnetization using a realistic band structure for cuprate superconductors.…”

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confidence: 99%