Magnetic orderings in La- and Y-substituted PrCo2Si2 compounds

Abstract The results of heat capacity ( C ), electrical resistivity ( ρ ) and magnetoresistance (Δ ρ / ρ ) measurements on the compounds Pr 1− x La x Co 2 Si 2 ( x =0, 0.2, 0.4, 0.6, 0.8, 1.0) and Pr 1− y Y y Co 2 Si 2 ( y =0.2, 1.0) are reported. The Pr sub-lattice dilution studies on the PrCo 2 Si 2 compound indicate that in spite of the anomalously high antiferromagnetic ordering temperature (31 K), the RKKY interaction is responsible for magnetic ordering in this compound. The paramagnetic to antiferromagnetic transition temperature in Pr 0.8 Y 0.2 Co 2 Si 2 is lower than that expected due to the positive chemical pressure effect. In contrast to the three magnetic transitions in PrCo 2 Si 2 at 31, 17 and 9 K, there are only two magnetic transitions in Pr 0.8 La 0.2 Co 2 Si 2 and Pr 0.8 Y 0.2 Co 2 Si 2 above 3 K. The Δ ρ / ρ of PrCo 2 Si 2 at 3 K is large (>20%) and positive for fields around 40 kOe. The metamagnetic transition observed in the Δ ρ / ρ data of Pr 1− x La x Co 2 Si 2 and Pr 0.8 Y 0.2 Co 2 Si 2 compounds has a systematic variation with composition.