  The spin-chain compounds, Ca3CuIrO6 and Ca3CuRhO6, crystallizing in a
K4CdCl6-derived monoclinic structure, are investigated by ac and dc
magnetization, isothermal remnant magnetization as well as heat capacity
measurements. The results reveal the existence of a magnetic ordering in the
vicinity of 15 K for both the compounds, but the transition appears to be of a
complex nature. The existence of a spin-glass component is strongly indicated
by the results. We propose that topological effects play a role on magnetism of
these compounds. The magnetic properties for these two compounds are
interestingly similar as though isoelectronic chemical substitution at the
octahedral coordination site does not significantly interfere in the magnetic
exchange process.
