"Mode-Selective Coupling of Coherent Phonons to the Bi2212 Electronic Band Structure"

S.-L. Yang: J. A. Sobota, Y. He, D. Leuenberger, H. Soifer, H. Eisaki, P. S. Kirchmann, and Z.-X. Shen; Physical Review Letters, 05/03/19.

Additional Authors: J. A. Sobota, Y. He, D. Leuenberger, H. Soifer, H. Eisaki, P. S. Kirchmann, and Z.-X. Shen

Abstract:

Cuprate superconductors host a multitude of low-energy optical phonons. Using time- and angleresolved photoemission spectroscopy, we study coherent phonons inBi2Sr2Ca0.92Y0.08Cu2O8+δ. Sub-meV modulations of the electronic band structure are observed at frequencies of 3.94±0.01 and 5.59 ±0.06 THz. For the dominant mode at 3.94 THz, the amplitude of the band energy oscillation weakly increases as a function of momentum away from the node. Theoretical calculations allow identifying the observed modes as CuO2-derived A1g phonons. The Bi- and Sr-derived A1g modes which dominate Raman spectra in the relevant frequency range are absent in our measurements. This highlights the mode selectivity for phonons coupled to the near-Fermi-level electrons, which originate from CuO2 planes and dictate thermodynamic properties.