Formation of a superlattice structure and suppression of the magnetic order in Ce1−xPbxPt2 (0 ⩽ x < 0.5)

• A new compound Ce1−xPbxPt2 was found to exist for 0 ⩽ x ⩽ 0.43.
• Single crystals of Ce1−xPbxPt2 (0 ⩽ x < 0.5) were grown by the self-flux method.
• The ternary alloys form a superlattice structure of C15b (MgSnCu4 type).
• The antiferromagnetic order of CePt2 is destroyed by the alloying with Pb.

The Laves phase compound CePt2 crystallizing in the cubic C15 (MgCu2 type) structure orders antiferromagnetically at 1.8 K. Single crystalline samples of Ce1−xPbxPt2 (0 < x < 0.5) have been prepared by the self-flux method. It is found that Pb atoms replace preferentially the Ce atoms in the face-center-cubic sublattice, forming a superlattice structure of the cubic C15b (MgSnCu4 type). We have measured the specific heat, magnetic susceptibility, and electrical resistivity. The results reveal that the Ce valence remains trivalent in Ce1−xPbxPt2 (x ⩽ 0.43) but the superlattice formation suppresses the antiferromagnetic ordering temperature below 0.35 K for x = 0.43.