NEUTRON DIFFRACTION STUDIES ON DY(CU1-XNIX)(2)SI-2

摘要

Neutron powder diffraction studies have been made for Dy(Cu1-xNix)(2)Si-2 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 (T-N = 10 K) and the Dy magnetic moment (8.2 mu(B)). The diffraction patterns of DY(Cu0.94Ni0.06)(2)Si-2 and DY(Cu0.9Ni0.1)(2)Si-2 are interpreted by the same commensurate antiferromagnetic structures with k = (1/2,0,1/2). The Neel temperatures of Dy(Cu0.94Ni0.06)(2)Si-2 and Dy(Cu0.9Ni0.1)(2)Si-2 are determined to be 7.5 and 6.5 K, respectively. The magnetic moments are 6.5 mu(B)/Dy in the Dy(Cu0.94Ni0.06)(2)Si-2 and 6.0 mu(B)/Dy in the Dy(Cu0.9Ni0.1)(2)Si-2. 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)(2)Si-2 which implies the existence of some kinds of short range ordering of Dy moments. This fact suggests that the local crystalline electric field with lowered symmetry breaks the perfect magnetic arrangement with k = (1/2,0,1/2). (C) 1997 American Institute of Physics. References: 10