  The effect of Ge substitution for Si in SmMMn2Si2-xGex compounds has been
studied. The Sm ordering temperature is found to be much larger in the compound
with x=2, as compared to the compounds with x=0 and 1. The increase in the
intra layer Mn-Mn distance is found to be responsible for this increase. Among
these three compounds, SmMn2Ge2 is found to show re-entrant ferromagnetism at
low temperatures. The magnetic contribution to the heat capacity has been found
in all the three compounds. The splitting of the ground state multiplet has
been estimated by fitting the magnetic part of the heat capacity data using the
Schottky formula. The isothermal magnetic entropy change is found to remain the
same for x=0 and 1, but decrease in the compound with x=2, though the nature of
magnetic transition changes from second order to first order, as x is increased
from 0 to 2. The electrical resistivity increases with Ge concentration. The
excess resistivity in the antiferromagnetic region has been calculated.
