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Hole redistribution in Sr\_(14-x)Ca\_xCu\_24O\_41 (x = 0, 12) spin ladder compounds: ^63Cu and ^17O NMR study under pressure

Y. Piskunov·D. Jérome·P. Auban-Senzier·P. Wzietek·A. Yakubovsky
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Abstract

We report the results of a ^63Cu and ^17O NMR study of the nuclear quadrupole interaction tensor, ^(17,63)nu\_{Q,alpha}, in the hole doped spin ladder system Sr\_(14-x)Ca\_xCu\_24O\_41 (x = 0 and 12) performed under ambient and high pressures. NMR data show that the hole density in the Cu\_2O\_3 ladder layer grows with temperature, Ca content and an applied pressure. We have derived the hole occupation of Cu 3d and O 2p orbitals at the different ion sites in the Cu\_2O\_3 ladder as a function of the temperature, Ca substitution and pressure. We also suggest that the most important role of high pressure for the stabilization of a superconducting ground state in Ca-rich two-leg ladders is an increase of the hole concentration in the conducting Cu\_2O\_3 planes. We have obtained an estimate of 0.10 hole per Cu1 for the hole concentration at low temperature in Ca12 under 32 kbar when this compound undergoes a superconducting transition at 5K. Such a value fits fairly well with the doping phase diagram of cuprate superconductors.

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Y. Piskunov, D. Jérome, P. Auban-Senzier, P. Wzietek, A. Yakubovsky. 2005-05-23. Hole redistribution in Sr\_(14-x)Ca\_xCu\_24O\_41 (x = 0, 12) spin ladder compounds: ^63Cu and ^17O NMR study under pressure. https://doi.org/10.1103/physrevb.72.064512

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