Measurement of the density of states of a Al6Ru quasicrystalline alloy by ultrafast thermomodulation

In this paper, we present results of time-resolved optical measurements of electron dynamics in the metastable quasicrystal Al6Ru. A hot electron distribution is photo-excited by femtosecond laser pulses and the relaxation rates of the hot electron distribution cooling are measured. These rates are observed to change drastically close to the Fermi level and our results are compatible with the presence of a strong depression in the density of states (DOS) over an energy range of approximately 45 meV. These features have been predicted from numerical calculations of the density of states in many quasicrystalline materials and ours are the first experimental results in the optical domain to confirm these predictions.