Interaction between localized and conduction-electron spins in the high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="italic">T</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="italic">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>superconductor Gd:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">EuBa</mml:mi></mml:mrow><mml:mrow><mml:mn

Shaltiel, D.; Noble, Christy; Pilbrow, John R.; Hutton, D. R.; Wałker, E.

doi:10.1103/physrevb.53.12430

Cited by 20 publications

(13 citation statements)

References 13 publications

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“…The X-band EPR spectra of our Gd3 +-doped 123 samples taken below 120-150 K [7] show a resolved fine structure consistent with the published data [8,9]. When temperature increases, the fine structure progressively collapses into one central line due to exchange coupling with delocalized charge carriers, in agreement with the Barnes-Plefka theory [10].…”

supporting

confidence: 77%

“…The data were found to be well correlated with those reported by Janossy et al [11] on 1% Gd-doped material, as well as with temperature dependence of the 89Y nuclear spin-lattice relaxation rate in similar substances [12]. Only the Korringa law above T T was claimed, however, in [9] (note that in both refs. 9 and 11 the Gd Ti values were extracted from the temperature-dependent part of the EPR linewidth).…”

supporting

confidence: 74%

“…Following the idea of Shaltiel et al [9], the high-field 5/2-7/2 EPR transition was used, which remains resolved till room temperatures. According to the theory of Barnes [10], in the case of pure magnetic dipolar selection rules, the ratio of relaxation contributions to the widths of the fine-structure components at S = 7/2 is 7:12:15:16:15:12:7 where 1/T 1 is taken as unity.…”

mentioning

confidence: 99%

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Spin gap, phase separation and d-wave pairing as revealed by electron spin-lattice relaxation in 123 and 124 YBaCuO systems doped with Gd3+

et al. 2000

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With an original modulation technique, the Gd 3 + electron spin-lattice relaxation has been investigated in normal and superconducting states of YBa 2 Cu306+x (123) and YBa2Cu4G8 (124) compounds doped with 1 % Gd. In the 123 sample with x = 0.9 (T = 90 K), the T, behavior within 50 < T < 200 K reveals the [1 -tanh 2 (zl/2kT)]/T dependence typical of a spin gap opening with A 240 K. Below 50 K, the exponential slowing down of T, is limited by the Korringa-like behavior (TI T = const); the same Korringa-like law is found in the 123 sample with x = 0.59 (T = 56 K) within the total 4.2-200 K temperature range. This is interpreted in terms of microscopic separation of the normal and superconducting phases allowing for the electron spin cross-relaxation between them.In the 124 sample (T = 82 K), the Gd3 + relaxation rate below 60 K is found to obey a power law T" with an exponent n 3. Such a behavior (previously reported for nuclear spin relaxation) is indicative of the d-wave superconducting pairing. Additional paramagnetic centers characterized by relatively slow spin-lattice relaxation are found in both 123 and 124 systems. A well-pronounced change in the Ti temperature dependence at TT 180-200 K is observed for these slowly relaxing centers as well as for the conventional, fast-relaxing Gd 3 + ions, suggesting microscopic phase separation and a change in the relaxation mechanism due to electronic crossover related with the opening of the spin gap. This hypothesis is supported by some "180 K anomalies" previously reported by other authors.Among the puzzles of high-Te physics, three problems attracted special attention but remained unsolved for years. First, the so-called spin gap (or pseudo gap) which opens in underdoped oxide superconductors well above T c ; second, a microscopical (or mesoscopical) phase separation of spins and charges in high-Tc materials; and, finally, the competition between s-and d-wave superconducting pairing below T. In our contribution, some information on these topics as obtained with the help of electron paramagnetic resonance (EPR) and, especially, electron spin-lattice relaxation will be presented.

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supporting

confidence: 77%

supporting

confidence: 74%

mentioning

confidence: 99%

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Spin gap, phase separation and d-wave pairing as revealed by electron spin-lattice relaxation in 123 and 124 YBaCuO systems doped with Gd3+

et al. 2000

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“…In these papers, however, the relaxation rate was determined from the temperature-dependent part of the EPR linewidth; as a result, the data were masked by strong inhomogeneous broadening, so only the high-temperature range was investigated. Note that the ordinary Korringa law (T1 T = const) was claimed by Shaltiel et al [6] at 80 < T < 300 K, without any evidence of the spin-gap effect known in the NMR relaxation in the underdoped 1-2-3 systems [7]. Such an effect was found, however, in the concentrated GdBa 2 Cu3Ox materials studied by the modulation technique [1].…”

Section: Yba2cu3 O Doped With Gdmentioning

confidence: 60%

“…So the paramagnetic Gd 3 + ions (partly replacing the diamagnetic Y3 +) can serve as a good spin probe to study electronic and magnetic states of this substance. Previously, the Gd spin relaxation in the 1-2-3 system was studied in [4][5][6]. In these papers, however, the relaxation rate was determined from the temperature-dependent part of the EPR linewidth; as a result, the data were masked by strong inhomogeneous broadening, so only the high-temperature range was investigated.…”

Section: Yba2cu3 O Doped With Gdmentioning

confidence: 99%

Electron spin-lattice relaxation in noncommon metals YBa2Cu3Ox and Rb1C60

1998

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Using an original modulation technique, the electron spin-lattice relaxation have been investigated in two noncommon metals: YBa2Cu3Ox, high-T material doped with 1% Gd, and Rb1C60, linear polymer phase fulleride. In the first case, the Korringa-like temperature dependence of the Gd 3 + longitudinal relaxation time T, is found for x = 6.59 in a wide temperature range 4.2 < T < 200 K, both above and below T = 56 K. At x = 6.95 (T = 90 K), the T, behavior within 50 < T < 200 K is evidently affected by spin gap opening with the gap value of about 240 K. At 200 K, an unexpected acceleration of the relaxation rate takes place, suggesting some change in the relaxation mechanism. The data are discussed in terms of the Barnes-Plefke theory with allowance made for microscopic separation of the normal and superconducting phases. In Rb,C 60 , the evolution of the ESR line and relaxation rates have been studied accurately in the range of the metal-insulator transition (below 50 K). Interpretation is suggested which takes into account breaking down the relaxation bottleneck due to opening of the energy gap near the Fermi surface. The gap value of about 100 cm-' is estimated from the analysis of relaxation rates, lineshape and spin susceptibilities.

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Oxygen content dependence of the EPR line shape in GdBa2Cu3O7−y single crystal

Bejjit

Haddad

2002

Appl. Magn. Reson.

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X-band electron paramagnetic resonance (EPR) spectra of a GdBa2Cu307_y single crystal were obtained at room temperature before and after reducing its oxygen content by annealing. Before annealing, the sample exhibited superconductivity at T c ~ 90 K; the EPR line was asymmetrical and was described with a Dysonian shape because of the skin effect. After annealing, superconductivity was not observed; the EPR line, less affected by the skin effect, was symmetrical and more intense, approximately described with a Lorentzian shape.

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Interaction between localized and conduction-electron spins in the high-Tcsuperconductor Gd:EuBa

Cited by 20 publications

References 13 publications

Spin gap, phase separation and d-wave pairing as revealed by electron spin-lattice relaxation in 123 and 124 YBaCuO systems doped with Gd3+

Spin gap, phase separation and d-wave pairing as revealed by electron spin-lattice relaxation in 123 and 124 YBaCuO systems doped with Gd3+

Electron spin-lattice relaxation in noncommon metals YBa2Cu3Ox and Rb1C60

Oxygen content dependence of the EPR line shape in GdBa2Cu3O7−y single crystal

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