Magnetic, magneto-thermal and magneto-transport properties in SmMn2Si2-xGex compounds

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.

Pramod Kumar, K. G. Suresh, A. K. Nigam, S. K. Malik · 2007