Magnetic properties of pseudo-ternaries of the composition Nd(Mn1−xCrx)2Si2

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Abstract
Structural and magnetic properties of a number of pseudo‐ternaries of the composition Nd(Mn1−xCrx)2Si2 have been examined. In the composition range 04‐type structure. Magnetic properties were examined between 4.2 K and 400 K in applied fields up to 20 kOe. NdMn2Si2 exhibits anomalies in the magnetization versus temperature plots at about 40 K and 380 K—the former due to the ordering of the rare earth moments and the latter due to the ordering of the transition metal sublattice. Addition of chromium to this compound increases the crystal cell volume significantly and modifies the magnetic behavior. The transition metal sublattice orders antiferromagnetically at 380 K, 260 K and 200 K for compositions of X=0, 0.2 and 0.3, respectively. Compounds of the composition X=0.2, 0.3 and 0.4 exhibit unusual thermomagnetic hystereses. The thermomagnetic curves for these compositions in low external fields (<10 kOe) exhibit an increase in the magnetization upon warming the sample from 4.2 K to about 30 K. Above this temperature the rare earth sublattice begins to disorder. These results are interpreted on the basis of a model considering the competition of exchange interactions of the rare earth and transition metal sublattices. The possibility of modifying the nature of magnetic interaction between rare earth and Mn atoms through the incorporation of a second transition metal atom (in this instance Cr) into the lattice will be discussed. Experimental data obtained for the compositions of X=0.2, 0.3 and 0.4 seem to indicate that the rare earth ion changes its easy direction of magnetization from the easy c‐axis to the basal plane (or cone) as the material is cooled below 50 K.