Neutron diffraction studies on Dy(Cu1-xNix)2Si2

Neutron powder diffraction studies have been made for Dy(Cu1−xNix)2Si2 with x=0, 0.06, and 0.1. The diffraction patterns of DyCu2Si2 are consistent with the reported magnetic structure [k=(1/2,0,1/2)], the Neel temperature (TN=10 K) and the Dy magnetic moment (8.2 μB). The diffraction patterns of Dy(Cu0.94Ni0.06)2Si2 and Dy(Cu0.9Ni0.1)2Si2 are interpreted by the same commensurate antiferromagnetic structures with k=(1/2,0,1/2). The Neel temperatures of Dy(Cu0.94Ni0.06)2Si2 and Dy(Cu0.9Ni0.1)2Si2 are determined to be 7.5 and 6.5 K, respectively. The magnetic moments are 6.5 μB/Dy in the Dy(Cu0.94Ni0.06)2Si2 and 6.0 μB/Dy in the Dy(Cu0.9Ni0.1)2Si2. The magnetic moment decreases as the Ni concentration increases, whereas the Dy moment determined by the Mossbauer spectroscopy increases as x increases. There is a strong diffuse peak at the (1/2 0 1/2) position of Dy(Cu0.94Ni0.1)2Si2 which implies the existence of some kinds of short range ordering of Dy moments. This fact suggests that the local crystalline el...