FEMTOSECOND ELLIPSOMETRY: A NEW TOOL FOR THE MEASUREMENT OF HOT ELECTRON MOMENTUM RELAXATION TIMES IN METALS

Abstract

Optical pump-probe measurements were performed with an elliptically polarised pump to observe the transient nonlinear polarisation due to the Specular Inverse Faraday Effect and the Specular Optical Kerr Effect in thin films of Au, Cu, Ag, Ni, Pd, Ti, Zr, and Hf under identical experimental conditions. The temporal shapes of the signals were used to extract characteristic time scales for the decay of the transient polarisation, which were interpreted in terms of scattering of the linear and angular momentum of hot electrons. A systematic variation of the signal magnitudes and temporal shapes was observed between different metals that reflects their underlying band structure.