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 Zn₅₆Mg₃₆Y₈, annealed ribbon samples of Zn₆₂Mg₃₀Y₈ and annealed ribbon samples of Zn₅₅Mg_35.5Gd_9.5 are 1, mΩ cm, 0.3, mΩ cm and 0.3, mΩ cm, respectively. The resistivities of all the samples decrease by 5-- 7$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.