Metamagnetism in YCo2 and LuCo2 is investigated in the spin-fluctuation the
ory, considering the contribution from both the zero-point and the thermal
spin fluctuation. The metamagnetic transition at low temperature and the te
mperature dependence of the paramagnetic susceptibility at finite temperatu
re are investigated in a self-consistent numerical calculation based on the
spin-fluctuation theory and good agreements with experimental results have
been obtained in a systematic way. It is shown that the effect of strong e
nhancement of the paramagnetic susceptibility and the electronic specific c
oefficient at low temperature can be explained satisfactorily by taking int
o consideration the zero-point spin fluctuation.