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Research
Electron-Phonon Coupling
In conventional superconductors, phonon mediated interactions attract
the electrons and form cooper pairs required for bose condensation
and zero resistance. In the high-Tc superconductors,
the boson that mediates the pairing—termed the “mechanism” of
superconductivity—has been long-debated. In ARPES, we
have found that the electrons are strongly coupled to a bosonic mode—exhibiting
a kink in the dispersion along the nodal (0, 0) - (π, π)
direction and evolving into an even stronger renormalization of the
dispersion in the anti-nodal (0, π) - (π, π) direction. This
anisotropy follows that of the d-wave gap, suggesting an intimate
connection to the superconductivity. We have, by comparing
with other spectroscopies that measure the phonons directly, identified
the bosonic mode as a phonon and one in particular that couples anisotropically
to the Fermi surface. This anisotropic electron-phonon interaction
may be a key ingredient to understanding high-Tcsuperconductivity.
