SPECIFIC-HEAT AND MAGNETIC-STRUCTURE OF GDT2X2 COMPOUNDS (T = CU, NI,X = SN, SB)

The magnetic specific heat of GdNi2Sn2, GdNi2Sb2 and GdCu2Sb2 shows a lambda-type anomaly at T-N with a noticeable reduction of the disconti nuity compared to that expected for a simple antiferromagnet. It can b e associated with the existence of amplitude modulated magnetic struct ure just below T-N. Above T-N a weak magnetic contribution is observed , evidencing tile short-range ordering. From neutron diffraction studi es it can be also concluded that investigated compounds have not simpl e antiferromagnetic structures. For GdNi2Sn2 the propagation vector Q = (0.3, 1/2, 1/2) was found with tile magnetic moments along the [1,0, 0] axis.