Anomalous transition from antiferromagnetic to ferromagnetic order in Tb1-xYxNiAl

We shall describe the change of magnetic order occurring in the pseudo-tern ary system Tb1-xYxNiAl, which was investigated in the range of 0 less than or equal to x less than or equal to 0.8 by ac- and de-susceptibility measur ements and neutron diffraction experiments. An anomalous transition from an tiferromagnetic to ferromagnetic order was observed. Characteristic feature s of the transition are (a) it occurs in a narrow range of the Y content be tween x=0.01 and x=0.05, (b) both types of magnetic order coexist in differ ent domains of the same compound, and (c) the preferred type of order chang es with temperature. [S0163-1829(99)01113-3].