Resonant inelastic x-ray scattering probes the electron-phonon coupling in the spin-liquid kappa-(BEDT-TTF)2Cu2(CN)3

TL;DR

This study uses resonant inelastic x-ray scattering to investigate the electron-phonon coupling in a spin-liquid insulator, revealing site-dependent phonon modes and quantifying their coupling strengths.

Contribution

It demonstrates the ability to selectively excite and analyze different phonon modes in a spin-liquid material using N K-edge RIXS, providing new insights into electron-phonon interactions.

Findings

Resolved harmonics of anion plane vibrations.

Site-dependent excitation of phonon modes.

Estimated site-specific electron-phonon coupling strengths.

Abstract

Resonant inelastic x-ray scattering at the N K edge reveals clearly resolved harmonics of the anion plane vibrations in the kappa-(BEDT-TTF)2Cu2(CN)3 spin-liquid insulator. Tuning the incoming light energy at the K edge of two distinct N sites permits to excite different sets of phonon modes. Cyanide CN stretching mode is selected at the edge of the ordered N sites which are more strongly connected to the BEDT-TTF molecules, while positionally disordered N sites show multi-mode excitation. Combining measurements with calculations on an anion plane cluster permits to estimate the sitedependent electron-phonon coupling of the modes related to nitrogen excitation.