In this study, we investigate the electronic structure and electron self-energy of palladium single crystals using polarization-dependent high-resolution angle-resolved photoemission spectroscopy. The observed Fermi surfaces and energy-band dispersions agree with those given by the band-structure calculation. A detailed comparison between the observed and theoretical band dispersions of the ${\Sigma }_1$ band forming the electronlike Fermi surface indicates an electron-electron coupling parameter of ${\lambda }_{ee}\sim 0.02$. Near the Fermi level, a kink structure in the energy-band dispersion exists at $\sim -20$ meV, in agreement with the Debye energy. The electron-phonon coupling parameter is estimated to be ${\lambda }_{ep}=0.39\pm 0.05$ at 8 K for the ${\Sigma }_1$ band, which is consistent with the theoretical values of ${\lambda }_{ep}=0.35–0.41$. Furthermore, analyses of the self-energy indicate a possible contribution from the electron-paramagnon interaction in the energy range of $-50\sim -150$ meV. The evaluated electron-paramagnon coupling parameter is ${\lambda }_{em}\sim 0.06$ for the ${\Sigma }_1$ band. We found that the magnitudes of ${\lambda }_{ep}$ and ${\lambda }_{em}$ depend on the Fermi surface points. The total effective mass enhancement factor is estimated to be $1+{\lambda }_{ep}+{\lambda }_{ee}+{\lambda }_{em}\sim 1.5$ for the ${\Sigma }_1$ band, which is close to the values $m^{*}/m_b\sim 1.5–1.7$ given by the de Haas–van Alphen and electron specific-heat measurements.

• Received 13 November 2012

DOI:https://doi.org/10.1103/PhysRevB.87.035140