  We have investigated critical phenomena in spin glasses RxY1-xRu2Si2 (R = Dy,
Tb, Gd). These compounds, where the magnetic moments of rare-earth ions
interact by the long-range Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction
via conduction electrons, has uniaxial magnetic anisotropy. The separation of
the zero-field-cooled and field-cooled magnetization was found only along the
c-axis in all compounds, and hence, they are classified into the long-range
Ising spin glass. The magnetic anisotropic energies in these compounds are
different from each other in two orders of magnitude, from 330 K to 1.8 K,
however, the critical exponents are similar. It clearly indicates a presence of
the universality of the long-range RKKY Ising spin glasses.
