  We report the electronic properties of R4PtAl (R = Ho, and Er), which
contains 3 sites for R, by the measurements of magnetization (ac and dc),
heat-capacity, transport, and magnetoresistance (MR). Dc magnetization data
reveal antiferromagnetic order below 19 K and 12 K in Ho and Er compounds,
respectively. Additional features observed at lower temperatures (12 K for
Ho4PtAl and 5 K for Er4PtAl) are akin to cluster spin-glass phase. Resistivity
data exhibit a weak minimum at a temperature marginally higher than their
respective N\'eel temperature (T_N) which is unusual for such rare-earths with
well localized 4f states. Isothermal magnetization and magnetoresistance data
well below T_N exhibit signatures of a subtle field-induced magnetic transition
for a small magnetic field (less than 10 kOe). Notably, the isothermal entropy
change at T_N has the largest peak value within this rare-earth family; for a
field change from zero to 50 kOe, the entropy change is about 14.5 J/kg K
(Ho4PtAl) and 21.5 J/kg K (Er4PtAl) suggesting a role of anisotropy of 4f
orbital in determining this large value. The results provide some clues for the
advancement of the field of magnetocaloric effect. The magnetocaloric property
of Er4PtAl is nonhysteretic meeting a challenge to find materials with
reversible magnetocaloric effect.
