Electronic transport in Al-Mn systems with icosahedral clusters

The electronic transport in alpha -Al-Mn(Si) is examined in view of the co- operation of Mackay icosahedra Al42Mn12. We calculate resistivities and res istances by means of the Kubo formula and the Buttiker formula, respectivel y. We find the following: (i) Large resistances result from the electronic coherence in the Mn subsystem just beyond the length scale of the unit cell . Most important in this respect is the orientation order of the Mackay ico sahedra. After randomizing the cluster orientation the system behaves like amorphous metals. (ii) Direct links between icosahedra via Al-glue atoms ca n considerably change the transport behavior (shifts of narrow spectral fea tures). (C) 2000 Elsevier Science B.V. All rights reserved.