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arXiv · 1706.01946

Dispersive charge density wave excitations and temperature dependent commensuration in Bi2Sr2CaCu2O8+δ

Laura Chaix·Giacomo Ghiringhelli·Yingying Peng·Makoto Hashimoto·Brian Moritz·Kurt Kummer·Nick B. Brookes·Yu He·Sudi Chen·Shigeyuki Ishida·Yoshiyuki Yoshida·Hiroshi Eisaki·Marco Salluzzo·Lucio Braicovich·Zhi-Xun Shen·Thomas P. Devereaux·Wei-Sheng Lee
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Abstract

Experimental evidence on high-Tc cuprates reveals ubiquitous charge density wave (CDW) modulations, which coexist with superconductivity. Although the CDW had been predicted by theory, important questions remain about the extent to which the CDW influences lattice and charge degrees of freedom and its characteristics as functions of doping and temperature. These questions are intimately connected to the origin of the CDW and its relation to the mysterious cuprate pseudogap. Here, we use ultrahigh resolution resonant inelastic x-ray scattering (RIXS) to reveal new CDW character in underdoped Bi2Sr2CaCu2O8+δ (Bi2212). At low temperature, we observe dispersive excitations from an incommensurate CDW that induces anomalously enhanced phonon intensity, unseen using other techniques. Near the pseudogap temperature T*, the CDW persists, but the associated excitations significantly weaken and the CDW wavevector shifts, becoming nearly commensurate with a periodicity of four lattice constants. The dispersive CDW excitations, phonon anomaly, and temperature dependent commensuration provide a comprehensive momentum space picture of complex CDW behavior and point to a closer relationship with the pseudogap state.

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Laura Chaix, Giacomo Ghiringhelli, Yingying Peng, Makoto Hashimoto, Brian Moritz, Kurt Kummer, Nick B. Brookes, Yu He, Sudi Chen, Shigeyuki Ishida, Yoshiyuki Yoshida, Hiroshi Eisaki, Marco Salluzzo, Lucio Braicovich, Zhi-Xun Shen, Thomas P. Devereaux, Wei-Sheng Lee. 2017-06-06. Dispersive charge density wave excitations and temperature dependent commensuration in Bi2Sr2CaCu2O8+δ. https://doi.org/10.1038/nphys4157

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