Experimental Determination of Momentum-Resolved Electron-Phonon Coupling

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• Electron-phonon coupling is crucial for understanding quantum materials.
• Quantifying this coupling, especially its momentum dependence, is experimentally challenging.
• Resonant inelastic x-ray scattering (RIXS) is a powerful probe of electronic and lattice excitations.

Purpose of the Study:

• To present a novel experimental method for quantitatively determining electron-phonon coupling and its momentum dependence using RIXS.
• To apply this method to a model cuprate system, NdBa2Cu3O6.
• To establish a general approach for investigating lattice dynamics in quantum materials.

Main Methods:

• Developed a RIXS-based experimental technique.
• Utilized detuning of incident photon energy from absorption resonances.
• Applied the method to the cuprate parent compound NdBa2Cu3O6.

Main Results:

• Successfully quantified electron-phonon coupling and its momentum dependence.
• Found the strongest electronic coupling to the oxygen half-breathing phonon at the Brillouin zone boundary.
• Determined the coupling strength to be approximately 0.17 eV at the Brillouin zone boundary.

Conclusions:

• The novel RIXS method provides quantitative electron-phonon coupling information.
• The findings in NdBa2Cu3O6 align with previous studies.
• This technique is broadly applicable to various RIXS-suitable resonances for studying quantum materials.