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Softening of Cu-O bond stretching phonon in tetragonal HgBa$_2$CuO$_{4+δ}$

H. Uchiyama·A. Q. R. Baron·S. Tsutsui·Y. Tanaka·W. -Z. Hu·A. Yamamoto·S. Tajima·Y. Endoh
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Abstract

Phonons in nearly optimally doped HgBa$_2$CuO$_{4+δ}$ were studied by inelastic X-ray scattering. The dispersion of the low energy modes is well described by a shell model, while the Cu-O bond stretching mode at high energy shows strong softening towards the zone boundary, which deviates strongly from the model. This seems to be common in the hole-doped high-$T_\mathrm{c}$ superconducting cuprates, and, based on this work, not related to a lattice distortion specific to each material.

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H. Uchiyama, A. Q. R. Baron, S. Tsutsui, Y. Tanaka, W. -Z. Hu, A. Yamamoto, S. Tajima, Y. Endoh. 2004-03-14. Softening of Cu-O bond stretching phonon in tetragonal HgBa$_2$CuO$_{4+δ}$. https://doi.org/10.1103/physrevlett.92.197005

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