Doping dependence of the electron–phonon and electron–spin fluctuation interactions in the high-Tc superconductor Bi2Sr2CaCu2O8+δ

Authors: E. Chia, D. Springer, S. Nair, X. Zou, S. Cheong, C. Panagopoulos, T. Tamegai, H. Eisaki, S. Ishida, S. Uchida, A. Taylor and J. Zhu

Published in: New Journal of Physics, 15, 103027, 2013.

Using ultrafast optical techniques, we detect two types of bosons strongly coupled to electrons in the family of Bi2Sr2CaCu2O8+δ (Bi-2212) from the underdoped to overdoped regimes. The different doping dependences of the electron–boson coupling strengths enable us to identify them as phonons and spin fluctuations: electron–phonon coupling (λe−ph) peaks at optimal doping, while electron–spin fluctuation coupling (λe−sf) decreases monotonically with doping. This observation is consistent with two facts: (i) superconductivity is in close proximity with antiferromagnetism at low dopings and (ii) a pronounced lattice renormalization effect at larger dopings.

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doi: 10.1088/1367-2630/15/10/103027