Evidence for Ba-site occupation of Pr3+ in Y1−xPrxBa2Cu3O7−δ from Cu NQR

Reyes, A. P.; Abdelrazek, M. M.; Kuhns, P. L.; Moulton, W. G.

doi:10.1016/s0921-4534(00)01032-7

Cited by 3 publications

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“…In this material, Pr +3 occupies the Ba +2 -site rather easily [59], in which case the Pr Ba defect disrupts the superconductivity in the BaO layer.…”

Section: Prba 2 Cu 3 0mentioning

confidence: 99%

BaO PLANES, NOT CuO₂ PLANES, CONTAIN HIGH-T_C SUPERCONDUCTIVITY

Dow

Harshman

2007

Int. J. Mod. Phys. B

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Muon spin rotation (p SR) measurements conducted on crystalline YBa 2 Cu 3 0 7 are consistent with s-wave pairing, not rf-wave, suggesting that the superconducting hole condensate resides in the BaO layers, not in the cuprate-planes. The specific heat and thermal conductivity data are explained by the superconducting BaO layers alone, unlike the failed interpretation based on Cu0 2 -plane superconductivity. The layer charges of the Cu0 2 planes are almost -2 lel, indicating that those planes are primarily carriers of electrons, not holes. The cuprate-planes are not the dominant hole-carriers of high-T c superconductivity, as demonstrated by doped YBa 2 Ru0 6 , which has no such Cu0 2 lanes, yet superconducts at ~ 93 K. Moreover the trio of related compounds, YSr 2 Ru0 6 (doped with Cu on Ru sites), undoped GdSr 2 Cu 2 Ru0 8 , and undoped Gd 2 _ ;: Ce ; ,Sr 2 Cu 2 RuOio all start superconducting near 49 K in their SrO layers, not in the cuprate planes of the two compounds that have such planes, because those planes are either antiferromagnetic or weakly ferromagnetic and so do not superconduct. In PrBa 2 Cu 3 0 7 , a Pr-on-Ba-site (Pr Ba ) defect kills the superconductivity, but Pr-on-Pr-site (Pr Pr ) does not. Both defects are approximately equidistant from the intervening cuprate plane, suggesting that the cuprate plane does not carry significant superconductivity. In GdBa 2 Cu 3 0 7 , Gd-on-a-Gd-site (Gd Gi ) does not break Cooper pairs, but Gd-on-a-Ba-site (Gd Ba ) does, indicating that the superconductivity is in the BaO layers, and not in the cuprate-planes. In HgBa 2 Ca"_ 1 Cu"0 2 " +2 , the BaO layers, not the cuprate-planes, gain positive charge as T C , pressure, and the number of layers n increase. The reason that theories based on holes in the cuprate-planes have done so poorly is that those planes were incorrectly identified as the source of high-temperature superconductivity on the basis of a single datum by Cava et al., that was first contradicted by Jorgensen et al., and then endorsed by Jorgensen alone on the basis of the Cava datum, not his own. This error is the main reason why cuprate-plane superconductivity, which probably does not exist, has been so widely accepted.

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“…In this material, Pr +3 occupies the Ba +2 -site rather easily [59], in which case the Pr Ba defect disrupts the superconductivity in the BaO layer.…”

Section: Prba 2 Cu 3 0mentioning

confidence: 99%