Collapse of antiferromagnetism induced by Ni-substitution in Eu(Pt1-xNix)2Si2

Abstract To clarify anomalous behaviour under high pressure in the antiferromagnet EuPt 2 Si 2 ( T N = 15 K ) , effects of substitution of Ni for Pt in EuPt 2 Si 2 are investigated. Eu ( Pt 1 - x Ni x ) 2 Si 2 is of single phase in the concentration range of 0 ⩽ x ⩽ 0.25 with preserving the identical crystal structure. The Ni-substitution decreases the lattice volume and the Neel temperature T N . For x ⩾ 0.20 the antiferromagnetism is collapsed completely. These phenomena correspond well to the behaviour under high pressure in EuPt 2 Si 2 and are associated with Eu valence variation toward a nonmagnetic trivalent direction.