Magnetic, magnetothermal, and magnetotransport properties in Sm Mn2 Si2-x Gex compounds

The effect of Ge substitution for Si in Sm Mn2 Si2-x Gex 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 intralayer Mn-Mn distance is attributed to this variation. Among these three compounds, Sm Mn2 Ge2 is found to show reentrant ferromagnetism at low temperatures. The magnetic contribution to the heat capacity has been calculated 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 decreases 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.