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Localisation of doped holes in edge-shared CuO_2 chain cuprates: consequences for dynamic spectral weight transfer

Z. Hu·S. -L. Drechsler·J. Malek·H. Rosner·R. Neudert·M. Knupfer·M. S. Golden·J. Fink·J. Karpinski·G. Kaindl·C. Hellwig·Ch. Jung
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Abstract

We present a joint experimental and theoretical study of the electronic structure of the cuprate chain systems A_(1-x)CuO_2 (A=Ca,Sr,Ba), as measured using O-K and Cu-L_3 x-ray absorption spectroscopy. The doping-dependent behaviour in these systems is radically different to that in conventional 2D cuprate networks formed from corner sharing CuO_4 plaquettes, and follows from the strongly suppressed inter-plaquette hybridisation resulting from the 90 degree Cu-O-Cu interaction pathway in the chain systems. Spectroscopically, this results in (a) a classical mixed-valent scenario whereby the different final states in the Cu-L_3 spectra can be used directly to 'read-off' the Cu valency and (b) a drastic reduction in the dynamic spectral weight transfer from the upper Hubbard band to the low energy scale in the O-K spectra. The final picture emerges of localisation of the doped holes, with the chain then comprised of a mixture of pure Cu(II)O_4 and Cu(III)O_4 plaquettes.

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Z. Hu, S. -L. Drechsler, J. Malek, H. Rosner, R. Neudert, M. Knupfer, M. S. Golden, J. Fink, J. Karpinski, G. Kaindl, C. Hellwig, Ch. Jung. 2001-08-08. Localisation of doped holes in edge-shared CuO_2 chain cuprates: consequences for dynamic spectral weight transfer. https://arxiv.org/abs/cond-mat/0108138

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