Intraband optical conductivityσ(ω,T)of Cu, Ag, and Au: Contribution from electron-electron scattering

Abstract

The intraband optical conductivity of all the noble metals has been measured at the temperatures 77, 295, and 425 K. In all cases the Drude scattering rate s ' = a{T)+P{Aco)' for fico less than about 2 eV. The temperaturedependent intercept u {T)may be attributed to electron-phonon scattering. The quadratic dependence on co, with P found to be temperature independent, is suggestive of electron-electron scattering. However, the observed values of P exceed current theoretical estimates by a factor of 2 or 3. Moreover, P should be related to the dc electrical and thermal resistivities {in the limited temperature regimes in which electron-electron scattering contributes appreciably). If this comparison is made, the discrepancy worsens to an order of magnitude. We briefly discuss other mechanisms which might account for the large observed values ofP, but none looks sufficient. We conclude that the frequency dependence in the Drude scattering rates of the noble metals, while qualitatively suggestive of electronelectron scattering, is quantitatively not understood.

Optical dielectric function of silver

“…[31,32] An analysis with extended Drude model extracts this frequency dependence, which is found to be consistent with Fermi liquid theory beyond 0.1 eV. [31,33,34] However, at energies below 0.1 eV τ (ω) rises more rapidly than suggested by the Fermi liquid theory possibly connecting to the Drude DC value of 40 fs. We discuss effects of impurity and grain boundary scattering, and note that even for samples prepared under nominally identical conditions, sample-to-sample variations can be as large as 30%…”

“…analysis. [34,72] Here, the Drude parameters have frequency dependence, which can be due to electron-electron interactions [33,34,61]. After introducing a frequency dependence to the Drude parameters, the Drude dielectric function in eq.…”

“…As a result, the free quasiparticle picture can explain the macroscopic response of the interacting electron system with frequency dependent renormalized effective electron mass m * and relaxation time τ . [33,59] In addition to these intrinsic effects, the Drude model has to be further modified by extrinsic effects such as surface, impurity, and grain boundary scattering.…”

Optical dielectric function of gold

“…The variation in optical dielectric function values between our EV, TS, and SC samples is significantly less than the variation in the literature through most of the spectrum. This suggests that the variations cannot be explained [6] 0.94 Johnson and Christy [1] 0.99 Parkins et al [46] 1.08 Rakic et al [11] 1.32 Svetovoy et al [30] 1.75…”

Spectroscopic ellipsometry study on the dielectric function of bulk Ti2AlN, Ti2AlC, Nb2AlC, (Ti0.5,Nb0.5)2AlC, and Ti3GeC2 MAX-phases

“…In Table I the values of collision energies 0 −1 are below 0.4 eV indicating that the free carrier behavior is limited to low energies. It should be mentioned that a frequencydependent collision time −1 = 0 −1 + ␤ 2 suggestive of electron-electron scattering 29 was considered but the results were not as good as those with a single relaxation time. Thus, the limited range of free carrier behavior makes a precise determination of the resistivity by optical means difficult.…”