Magnetoresistance in i-R-Cd icosahedral quasicrystals (R=Y, Gd)

We use magnetoresistance (MR) to probe the electronic properties of the recently discovered binary quasicrystals (QCs) i-Gd-Cd and i-Y-Cd, with and without local magnetic moments, respectively. DC magnetization has revealed spin-glass freezing in i-Gd-Cd at a temperature $T_f = 4.6$~K. MR was measured at $1.6\leq T$(K)$\leq 300$ and in magnetic fields $H$ up to 12~T. %In the MR measurements, The most interesting behavior is observed in i-Gd-Cd, in which the MR exhibits thermo-magnetic history dependence at low $T$. In particular, there is a clear difference between the ZFC and FC values of the low-field positive MR. In contrast, the i-Y-Cd MR does not depend on magnetic history. The onset of the history dependent MR at $T\sim 20$~K~$>T_f$, when the QC with local magnetic moments is cooled in a high field of 12~T, may be related to the formation of magnetic clusters above $T_f$, as inferred from the magnetization and specific heat studies. Possible mechanisms responsible for the striking coupling between charge transport and local magnetic environment observed in the MR will be discussed.