  We report magnetic behavior of two intermetallics-based kagome lattices,
Tb3Ru4Al12 and Er3Ru4Al12, crystallizing in the Gd3Ru4Al12-type hexagonal
crystal structure, by measurements in the range 1.8-300 K with bulk
experimental techniques (ac and dc magnetization, heat-capacity and
magnetoresistance). The main finding is that the Tb compound, known to order
antiferromagnetically below (T_N=) 22 K, shows glassy characteristics at lower
temperatures (<15K), thus characterizing this compound as a re-entrant
spin-glass. The data reveal that glassy phase is quite complex and is of a
cluster type. Since the glassy behavior was not seen for the Gd analogue in the
past literature, this finding for the Tb compound emphasizes that this kagome
family could provide an opportunity to explore the role of higher order (such
as quadrupole) in bringing out magnetic frustration. Additional findings
reported here for this compound are: (i) The temperature dependence of magnetic
susceptibility and electrical resistivity in the range 12 - 20 K are found to
be hysteretic leading to a magnetic phase in this temperature range, mimicking
disorder-induced first-order magnetic phase-transition. (ii) Features
attributable to an interesting magnetic phase co-existence phenomenon in the
magnetoresistance in zero field, after cycling across metamagnetic transition
fields, are observed. With respect to the Er compound, we do not find any
evidence for long-range magnetic ordering down to 2 K, but this appears to be
on the verge of magnetic order at 2 K.
