MOMENTUM DISTRIBUTION OF VALENCE-ELECTRONS IN A SINGLE AL-LI-CU ICOSAHEDRAL QUASI-CRYSTAL

A single Al59.3Li29.3Cu11.4 icosahedral quasicrystal is prepared with the Bridgman method. To study the electronic structure of this phase, high resolution Compton profiles along the axes of the five- and two-f old symmetries of the single quasicrystal phase have been measured wit h 60-keV synchrotron radiation X-rays. The Fermi cutoffs are observed clearly in the profiles. Anisotropy in the electron momentum distribut ion is not found. Although the valence electron profiles can be fitted with an inverted parabola, the free-electron model does not explain t he shape of profiles and the momentum values of the Fermi cutoffs. Bas ed on a concept of the quasi-Brillouin zone boundary the effects of st rong electron-lattice interaction on the electron momentum distributio n have been examined.