Scaling Effects in Al72Mn22Si6 Quasicrystals Deduced from the Pressure and Temperature Dependence of the Resistance

Abstract

AbstractX-ray diffraction and resistivity measurements on the Al72Mn22Si6 (Al-Mn-Si) rapidly quenched alloy are reported. The x-ray pattern shows that the alloy is essentially single phase, with a little mixture of unreacted Al. The peaks can be indexed using icosahedral vectors in the six dimensional space Z6. The resistance of thin ribbons of Al72Mn22Si6 quasicrystals has been measured as a function of temperature between 1.4 and 300 K at fixed pressures in the range 0 to 15 Kbar. Below 40 K, the resistance increases with decreasing temperature, and below 14 K, the conductivity varies as T1/2. This result is in agreement with the scaling and localization models in which spatial disorder and electron-electron correlation effects determine the electronic transport properties of the material. The value of the magnetoresistance measured at 60 KGauss and 0.34 K agrees qualitatively with the predictions of the above models. The pressure dependence of the correlation gap and the resistivity suggests that the system is in the strong coupling limit. In this regime, the functional dependence of the correlation energy on resistivity is Δ ~ ρ-2.