Composition-dependent electrical resistivity in an Al-Re-Si 1/1-cubic approximant phase: An indication of electron confinement in clusters

We report the synthesis of alpha -AlReSi and show that it is a 1/1-cubic ap proximant phase of the icosahedral quasicrystal with a = 12.9 Angstrom. The trend of the resistivity of the new approximant phase shows a nonmetallic character, similar to those seen in the stable icosahedral phases. The resi stivity depends sensitively on the Re concentration and the nonmetallic tra nsport is observed only at the Re concentration close to 17.4 at. %, where the transition metal sites in the icosahedral cluster are exclusively occup ied by Re atoms. In view of a recent ab initio calculation, the present res ult suggests strongly the formation of the virtual bound states, or confine ment of electrons, in the icosahedral clusters of transition metal atoms.