Lattice dynamics in single-crystal iridium

Iridium, a noble metal with a simple FCC crystal structure, serves as an ideal model for examining electron-phonon interactions. Electron-phonon scattering plays a central role in affecting both electron and phonon dynamics, ultimately influencing electron and thermal transport properties. However, neutron scattering studies have historically been limited by iridium's high neutron absorption cross-section. In this research, we investigate the lattice dynamics of iridium single crystals using the ARCS inelastic neutron scattering instrument at the Spallation Neutron Source. By combining Density Functional Theory (DFT) calculations with inelastic neutron scattering (INS) experiments, we explore high-temperature phonons and electron-phonon interactions. We observe that anharmonic effects partially obscure electron-phonon coupling, complicating the observation of Kohn anomalies in the neutron scattering data. Nonetheless, our findings reveal Kohn anomalies near the Brillouin zone K and X points, highlighting strong electron-phonon coupling in iridium.