Electron transport in Al65Cu20Co15-xFex quasicrystals

Abstract

We have studied the electrical resistivity and magnetoresistance for the system Al65Cu20Co15-xFex (0 less than or equal to x less than or equal to 15). The sample with x=0 could be indexed as the decagonal (D) phase, whereas the sample with x=15 forms the icosahedral (I) phase. The sample with intermediate x (2.5 less than or equal to x less than or equal to 12.5), however, consists of both phases. The temperature coefficient of the resistivity (TCR) is positive when x less than or equal to 17.5. The magnitude of the TCR for these samples is smaller than for icosahedral alloys. However, the other samples exhibit a negative TCR except below 30 K. The magnetoresistance of the samples with pure I or D phase, exhibits an increase of over 1% in a field of 45 kOe. The samples with intermediate x on the other hand, show relatively smaller increases. These results have been analyzed qualitatively in the framework of existing models. (C) 1997 Elsevier Science S.A.