  Motivated by the recent discovery of superconductivity in infinite-layer
nickelate thin films, we report on a synthesis and magnetization study on bulk
samples of the parent compounds ${R}$NiO$_{2}$ (${R}$=La, Pr, Nd). The
frequency-dependent peaks of the AC magnetic susceptibility, along with
remarkable memory effects, characterize spin-glass states. Furthermore, various
phenomenological parameters via different spin glass models show strong
similarity within these three compounds as well as with other rare-earth metal
nickelates. The universal spin-glass behaviour distinguishes the nickelates
from the parent compound CaCuO$_{2}$ of cuprate superconductors, which has the
same crystal structure and $d^9$ electronic configuration but undergoes a
long-range antiferromagnetic order. Our investigations may indicate a
distinctly different nature of magnetism and superconductivity in the bulk
nickelates than in the cuprates.
