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Ishida, K.; Kitaoka, Y.; Yamazoe, Kazuaki; Yamada, Yuh

doi:10.1103/physrevlett.76.531

Cited by 71 publications

(85 citation statements)

References 15 publications

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“…However, note that if a spinfluctuation mediated mechanism is assumed for the dwave pairing, then the effects of the impurity on the pairing potential need to be taken into account as well as the scattering of the quasiparticles by the impurity. This is because it is already known in the normal state that in the local environment of the impurity the spinfluctuations are strongly modified [1][2][3][4][5][6][7][8][9][10].…”

Section: Nature Of the Effective Impurity Potentialmentioning

confidence: 99%

“…In particular, it has been found that the nonmagnetic impurities significantly influence the magnetic correlations in the normal state [1][2][3][4][5][6][7][8][9][10]. The 89 Y NMR experiments [1,4] find that when Zn is substituted into YBa 2 Cu 3 O 6+x , the Knight shifts of the Y sites near the impurity are strongly enhanced as the temperature is lowered.…”

Section: Introductionmentioning

confidence: 99%

“…The T −1 1 measurements have been also carried out for Cu (2) in Zn substituted YBa 2 Cu 3 O 7 [8] and YBa 2 Cu 4 O 8 [9] systems. The effects of the nonmagnetic impurities on the magnetic correlations were also studied in La 1.85 Sr 0.15 CuO 4 with Al impurities [10].…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Knight shift data on Li and Zn substituted YBa2Cu3O6+x

Bulut

2001

Physica C: Superconductivity

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The Knight shift data on Li and Zn substituted YBa2Cu3O6+x are analysed using an itinerant model with short-range antiferromagnetic correlations. The model parameters, which are determined by fitting the experimental data on the transverse nuclear relaxation rate T −1 2 of pure YBa2Cu3O6+x, are used to calculate the Knight shifts for various nuclei around a nonmagnetic impurity located in the CuO2 planes. The calculations are carried out for Li and Zn impurities substituted into optimally doped and underdoped YBa2Cu3O6+x. The results are compared with the 7 Li and 89 Y Knight shift measurements on these materials.

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Section: Nature Of the Effective Impurity Potentialmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of the Knight shift data on Li and Zn substituted YBa2Cu3O6+x

Bulut

2001

Physica C: Superconductivity

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“…It is worth noting that non-magnetic impurities (i.e. spinless with S = 0, such as Zn 2+ [30][31][32][33], Mg 2+ [34], Li + [35] and Al 3+ [36]) that substitute the Cu 2+ -ions in the CuO 2 plane can induce local magnetic moments that significantly perturb the immediate vicinity of the impurity site, yielding suppression of superconductivity at T < T c and strong effects on the spin dynamics at T > T c . On the other hand, magnetic impurities (such as Ni 2+ with S = 1) are coupled to the background spin fluctuations via exchange interaction, and therefore act as weaker and more local scattering sites [30,31].…”

Section: Effects Of Spinless (S=0) Impuritiesmentioning

confidence: 99%

Spatial homogeneity and doping dependence of quasiparticle tunneling spectra in cuprate superconductors

Yeh¹,

Chen²,

Hammerl³

et al. 2001

Physica C: Superconductivity and its Applications

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Scanning tunneling spectroscopy (STS) studies reveal long-range (~100 nm) spatial homogeneity in optimally and underdoped superconducting YBa 2 Cu 3 O 7−δ (YBCO) single crystals and thin films, and macroscopic spatial modulations in overdoped (Y 0.7 Recently, it has been proposed that the interaction of nodal quasiparticles with thermally induced vortex loops [7] may give rise to the MFL behavior in the normal state and below the pseudogap temperature (T*) [13]. Generally speaking, an important consequence of the d-wave pairing symmetry is the presence of nodal quasiparticles at low temperature, and that of strong phase fluctuations is the separation of the pair formation temperature (T MF ~ T*) from the superconducting transition temperature (T c ) [7], with T c << T*. Given the fact that the low-energy excitations are important manifestations of the pairing state, we expect nodal quasiparticles to play a major role in determining the physical properties of the cuprates. On the other hand, if the Fermi surface were fully gapped due to broken time-reversal (T) symmetry in the pairing state, as suggested by certain theories [14,15], the lowenergy excitation spectra at T << T* would have been modified significantly. It is therefore important to establish the purity and possible doping dependence of the pairing symmetry in the cuprate superconductors. In particular, whether a small broken T-symmetry component may exist in the form of (d x 2 -y 2+id xy ) or (d x 2 -y 2+is) pairing should be carefully examined. In this work, we report studies of the quasiparticle tunneling spectra on the YBa 2 Cu 3 O 7-δ (YBCO) system over a wide range of doping levels. Several key results are noteworthy. First, we observed long-range (~ 100 nm)

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“…However, SDW appears to be a robust feature induced by the impurity, which should be observable in neutron scattering experiments. Nuclear magnetic resonance (NMR) measurements have shown that when a Cu 2+ in the Cu-O plane is substituted by a strong nonmagnetic impurity, such as Zn 2+ , an effective magnetic moment can be induced on the Cu sites around the impurity site [22,23,24,25]. More recent NMR measurements [25] show for the first time that near optimal doping, the Kondo screening effect observed above the superconducting transition temperature, is strongly reduced in the superconducting state.…”

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confidence: 99%

Spin and Charge Order around Vortices and Impurities in High-TcSuperconductors

2002

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By solving self-consistently an effective Hamiltonian including interactions for both antiferromagnetic spin-density wave (SDW) and d-wave superconducting (DSC) orderings, a comparison study is made for the local magnetic structure around superconducting vortices and unitary impurities. To represent the optimally doped regime of cuprates, the parameter values are chosen such that the DSC is dominant while the SDW is vanishingly small. We show that when vortices are introduced into the superconductor, an oscillating SDW is induced around them. The oscillation period of the SDW is microscopically found, consistent with experiments, to be eight lattice constants (8a0). The associated charge-density wave (CDW) oscillates with a period of one half (4a0) of the SDW. In the case of unitary impurities, we find a SDW modulation with identical periodicity, however without an associated CDW. We propose neutron scattering experiments to test this prediction.PACS numbers: 74.62.Dh The common feature of all high-transition-temperature (high-T c ) cuprates is the proximity between antiferromagnetic (AF) and d-wave superconducting (DSC) phases controlled by the doping-At low temperatures, the AF order of the parent compounds is replaced by a DSC order upon doping. The main theme of high-T c superconducivity research centers on how to establish the connection between these two kinds of orderings, i.e., whether they exclude each other, or coexist microscopically. In one of the strategies, the interplay between the AF and DSC ordering is explored by weakening the superconductivity in the optimally or slightly overdoped regime. The inelastic neutron scattering (INS) measurements on both optimally doped and underdoped La 2−x Sr x CuO 4 (LSCO) samples by Lake and co-workers provide the first evidence of the field-induced magnetic order [1,2]. The field-induced spin fluctuations have a spatial periodicity of 8a 0 with the wave vector pointing along the Cu-O bond directions. The principle magnetization oscillations in the vortex state are coherent over a distance L M > 20a 0 , substantially longer than the superconducting coherence length ξ 0 (∼ 5a 0 ). The field-induced enhancement of the Bragg peak intensity was also observed by Khaykovich et al. [3] in the elastic neutron scattering (ENS) measurement on a related material, La 2 CuO 4+y (LCO), but with L M > 100a 0 , indicating the existence of the field-induced static AF order of 8a 0 periodicity. Strong AF fluctuations have also been observed by Mitrovic et al.[4] in a high-field nuclear magnetic resonance (NMR) imaging experiment on nearoptimally doped YBa 2 Cu 3 O 7−x (YBCO). More recently, the scanning tunneling microscopy imaging by Hoffman et al.[5] has revealed the quasiparticle states around the vortex cores in slightly overdoped Bi 2 Sr 2 CaCu 2 O 8+x (BSCCO) a Cu-O bond-oriented "checkboard" pattern with 4a 0 periodicity. The periodicity (4a 0 ) of charge modulation is one half of that (8a 0 ) of the field-induced SDW modulation. Theoretically, Demler and co-workers, ...

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Al NMR Probe of Local Moments Induced by an Al Impurity in High-TcCuprateLa1.85

Cited by 71 publications

References 15 publications

Analysis of the Knight shift data on Li and Zn substituted YBa2Cu3O6+x

Analysis of the Knight shift data on Li and Zn substituted YBa2Cu3O6+x

Spatial homogeneity and doping dependence of quasiparticle tunneling spectra in cuprate superconductors

Spin and Charge Order around Vortices and Impurities in High-TcSuperconductors

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