Magnetic and transport properties of single-grain R-Mg-Zn icosahedral quasicrystals [R = Y, (Y1-xGdx), (Y1-xTbx), Tb, Dy, Ho, and Er]

We report measurements of the de magnetization, the low-held ac magnetic su sceptibility, and the electrical resistivity of large (up to 0.5 cm(3)) sin gle-grain samples of icosahedral R-Mg-Zn (R = Y, Tb, Dy, Ho, and Er). The d c magnetization and ac magnetic susceptibility data both indicate that icos ahedral Tb-Mg-Zn and Dy-Mg-Zn undergo a transition to a spin-glass state at T-f = 5.8 and 3.6 K, respectively, while low-temperature ac susceptibility measurements show that T-f = 1.95 and 1.3 K for Ho-Mg-Zn and Er-Mg-Zn, res pectively. For the series of solid solutions (Y1-xTbx)-Mg-Zn, the freezing temperature T-f varies approximately as x(2/3). The (Y1-xGdx)-Mg-Zn solid s olutions have lower T-f values than (Y1-xTbx)-Mg-Zn for the same magnetic r are-earth concentrations (x), indicating that local moment anisotropy cause d by crystalline electric-field effects plays a significant role in increas ing T-f. On the other hand, angular-dependent studies show that the de magn etization for T > T-f is isotropic within the experimental uncertainty. The electrical resistivity rho(T) of the single-grain samples is only weakly t emperature dependent, with a small, negative d rho/dT. Absolute values of t he resistivity fall in the range between 150 and 200 mu Omega cm, which is distinctly lower than the values previously reported for other thermodynami cally stable icosahedral quasicrystals. [S0163-1829(99)05801-4].