Electrical Properties of Zn-Mg-RE (RE=Y, Gd) Icosahedral Quasicrystals

Abstract

The electrical resistivity and the magnetoresistance have been measured for icosahedral phases of Zn–Mg–RE (RE=Y, Gd). Electrical resistivities of bulk samples of Zn 56 Mg 36 Y 8 , annealed ribbon samples of Zn 62 Mg 30 Y 8 and annealed ribbon samples of Zn 55 Mg 35.5 Gd 9.5 are 1 mΩcm, 0.3 mΩcm and 0.3 mΩcm, respectively. The resistivities of all the samples decrease by 5∼7% from 4.2 K to 273 K. At low temperatures, the conductivity of Zn–Mg–Y obeys T 1/2 dependence, while the resistivity of Zn–Mg–Gd obeys ln T dependence, where Gd atoms bear magnetic moments. In Zn–Mg–Y, the magnetoresistance is negative and insensitive to temperature, while in Zn–Mg–Gd it is positive in a low field range and becomes negative at high field with its magnitude larger at lower temperature. These results are interpreted by the theories of electron-electron interaction, weak localization and s-d exchange interaction.