Spinless Impurities in Cuprates: Local Magnetism and Kondo Effect in the Normal and Superconducting States

Alloul, H.; Bobroff, J.; Mendels, P.; Rullier‐Albenque, F.

doi:10.1142/s0217979202013742

Cited by 4 publications

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“…Although many qualitative and materials aspects are revealed by the experiments involving impurity substitutions, such observations are even harder to analyze theoretically than those done in the undoped AF case (see however Section V). (Alloul et al, 2000)).…”

Section: Impurities In the Af Phasesmentioning

confidence: 99%

“…The nuclear spin lattice relaxation T 1 of the nuclear spins are governed by the fluctuations of the local fields induced by the dynamic susceptibility (Pennington and Slichter, 1990). Modifications of the T 1 rates of the pure system due to local moment fluctuations are seen on nuclei even at large distances from the local moment, but are usually very hard to analyze due to the distribution of coupling constants (Alloul and Bernier, 1973). The most reliable experimental situation is that for which a well defined nuclear spin site with respect to the impurity can be singled out (Alloul, 1977).…”

Section: Spin Dynamicsmentioning

confidence: 99%

“…The phase diagram becomes then similar to that of Fig.2. Notice that the onset of pseudogap opening T * is not modified by Zn substitution (Figure taken from(Alloul et al, 2000)).…”

mentioning

confidence: 99%

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Defects in correlated metals and superconductors

et al. 2009

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In materials with strong local Coulomb interactions, simple defects such as atomic substitutions strongly affect both macroscopic and local properties of the system. A nonmagnetic impurity, for instance, is seen to induce magnetism nearby. Even without disorder, models of such correlated systems are generally not soluble in 2 or 3 dimensions, and so few exact results are known for the properties of such impurities. Nevertheless, some simple physical ideas have emerged from experiments and approximate theories. Here, we first review what we can learn about this problem from 1D antiferromagnetically correlated systems. We then discuss experiments on the high Tc cuprate normal state which probe the effect of impurities on local charge and spin degrees of freedom, and compare with theories of single impurities in correlated hosts, as well as phenomenological effective Kondo descriptions. Subsequently, we review theories of impurities in d-wave superconductors including residual quasiparticle interactions, and compare with experiments in the superconducting state. We argue that existing data exhibit a remarkable similarity to impurity-induced magnetism in the 1D case, implying the importance of electronic correlations for the understanding of these phenomena, and suggesting that impurities may provide excellent probes of the still poorly understood ground state of the cuprates.Comment: 66 pages, 48 figures, review articl

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Section: Impurities In the Af Phasesmentioning

confidence: 99%

Section: Spin Dynamicsmentioning

confidence: 99%

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Defects in correlated metals and superconductors

et al. 2009

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“…However, recent numerical calculation using Gützwiller approximation indicates that the frozen staggered moments are locally reduced by Zn in the superconducing state of a moderately doped two-dimensional t − J model [12]. According to this theory, the zero bias resonance peak in the local density of states and the local staggered moments are exclusive at T =0 K. It remains to be solved whether the Zn strengthens [13,14] or weakens [15] local magnetic correlation around Zn in the optimally doped or overdoped system.…”

Section: Introductionmentioning

confidence: 99%

Zn-neighbor Cu NQR in Zn-substitutedYBa2Cu3O7

Itoh

Machi²,

Kasai³

et al. 2003

Phys. Rev. B

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We studied local electronic states near Zn in optimally doped YBa2(Cu1−xZnx)3O 7−δ and underdoped YBa2(Cu1−xZnx)4O8 via satellite signals of plane-site Cu(2) nuclear quadrupole resonance (NQR) spectra. From the relative intensity of Cu NQR spectra, the satellite signals are assigned to Zn-neighbor Cu NQR lines. The Cu nuclear spinlattice relaxation time of the satellite signal is shorter than that of the main signal, which indicates that the magnetic correlation is locally enhanced near Zn both for the underdoped and the optimally doped systems. The pure YBa2Cu4O8 is a stoichiometric, homogenous, underdoped electronic system; nevertheless, the Zn-induced inhomogeneous magnetic response in the CuO2 plane is more marked than that of the optimally doped YBa2Cu3O 7−δ . 74.25.Nf, 74.72.Bk

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“…Individual virtual bound states around Zn and Ni impurities are actually observed by STS technique [100,101]. It remained to be solved whether the Zn strengthens [102,103] or weakens [91] local magnetic correlation around Zn in the optimally doped and overdoped systems and how the magnetic correlation near and away from Zn is changed or unchanged below and above T c . Zn-neighbor NMR and NQR measurements were highly desired.…”

Section: Normal-state Pseudo Spin-gapmentioning

confidence: 99%

Recent advances of NMR and NQR studies of YBa2Cu3O7-d and YBa2Cu4O8

Itoh

2007

Preprint

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Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) techniques have supplied us with unique information on local incoherent phenomenon as well as low frequency magnetic response of electronic systems. Some of recent advances in the studies of high-Tc cuprate superconductors are based on site-selective measurements of the local electronic state and the local electron spin dynamics. High-Tc superconductors YBa2Cu3O 7−δ (the optimal Tc = 93 K) and YBa2Cu4O8 (Tc = 82 K) with double-layer CuO2 planes have been studied by NMR and NQR techniques. From the intensive studies at the early stage, two-dimensional antiferromagnetic spin fluctuations and pseudo spin-gap in the magnetic excitation spectrum turned out to be key ingredients to characterize the novel electronic states, associated with the occurrence of superconductivity. Wipeout effect is a new key to characterize superconductor-insulator boundary in the lightly doped regime and impurity substitution effects. What happens near in-plane impurities and inside vortex cores in such novel electronic states? Nonmagnetic impurity Zn decreases Tc of the d-wave superconductivity because of the breakdown of Anderson theorem. From the careful NMR and NQR studies, it was concluded that the pseudo spin-gap in the normal state is robust for the substitution of nonmagnetic impurity Zn and magnetic impurity Ni. In the vicinity of a superconductor-insulator boundary induced by impurity, however, the pseudo spin-gap is suppressed. Collapse of low energy pseudo spin-gap due to the heavily substituted impurity Zn was also evidenced by neutron scattering measurements. For the impurity-substituted samples and in the vortex state of pure samples, the characteristic NMR and NQR spectra were observed. The local enhancement of magnetic correlation near the impurity Zn and inside the vortex core was observed from the frequency distribution of nuclear spin-lattice relation time T1. Scanning tunneling spectroscopy detects local density of states of electrons near Zn in the superconducting state. NMR and NQR experiments detect the local magnetism near Zn and inside the vortex cores.

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Spinless Impurities in Cuprates: Local Magnetism and Kondo Effect in the Normal and Superconducting States

Cited by 4 publications

References 0 publications

Defects in correlated metals and superconductors

Defects in correlated metals and superconductors

Zn-neighbor Cu NQR in Zn-substitutedYBa2Cu3O7

Recent advances of NMR and NQR studies of YBa2Cu3O7-d and YBa2Cu4O8

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