Electron–phonon coupling and related transport properties of metals and intermetallic alloys from first principles

Abstract

The fundamental scattering mechanisms between electrons and phonons in metals and metallic alloys dictate a wide range of phenomena in their materials’ physics. Using first-principles calculations carried out on dense electron and phonon wavevector grids, we determine the mode-level descriptions of electron–phonon interactions for nine characteristic metals, shedding light on their electrical and thermal transport properties at a range of electron and phonon temperatures. Our results reveal that even though there are similarities between the phonon densit of states of various simple metals, the electronic structure can significantly affect the modal contributions to electron–phonon coupling in metals. More specifically, we find that in the free-electron-like aluminum, the longitudinal high-frequency phonons contribute significantly to the mass enhancement parameter, whereas transverse phonons dominate the electron–phonon coupling in the noble metals with high density of d-band electrons near the Fermi level. In contrast, for intermetallic copper–gold alloys and superconducting metals such as Nb and Ta, the spectral contributions are mostly determined by the phonon density of states. The temperature-dependent volumetric electron–phonon coupling factor depends strongly on the electronic structures of the metals as it increases for the noble metals and their intermetallic alloys, decreases for Nb and Ta, and demonstrates a non-monotonic change for Al. For copper–gold alloys, the electron–phonon coupling strength and the volumetric electron–phonon coupling factor cannot be taken as the geometric mean of the two metals and are relatively much larger than that of their elemental constituents. We also find that the electron thermal conductivity of the 50/50 CuAu alloy is relatively higher than that of Cu3Au and CuAu3, and the electron thermal conductivities of the 25/75 and 75/25 alloys are similar to experimental measurements of disordered copper–gold alloys with the same compositions.