COMPARISON OF THE DIELECTRIC FUNCTION OF ALPD, AL3PD, AND AL70PD20MN10 DETERMINED BY ELECTRON-ENERGY-LOSS MEASUREMENTS

Electron-energy-loss measurements on crystalline AlPd and Al3Pd as wel l as on quasicrystalline Al70Pd20Mn10 are evaluated in terms of optica l constants using the Kramers-Kronig analysis. Interband transitions i n AlPd are identified, and found to be in agreement with those obtaine d from the theoretical density of states, whereas spectra of Al3Pd are dominated by plasmon excitations due to the quasifree electrons of Al . For Al70Pd20Mn10, the optical properties are strikingly similar to t hose of AlPd, except for an additional low-energy transition due to th e Mn d-derived states, manifesting a predominant Al-Pd interaction in the quasicrystal. [S0163-1829(97)06040-2].