The magnetic properties of the hexagonal compounds Tb(Ni1-xCUx)(5), wi
th x = 0.2, 0.6 and 0.8, at small applied magnetic fields have been st
udied in polycrystalline samples by AC susceptibility and magnetizatio
n measurements. We show that all compounds present a helimagnetic phas
e at a field smaller than the critical one which changes with concentr
ation. (C) 1998 Elsevier Science B.V. All rights reserved.