Anomalous transition from antiferromagnetic to ferromagnetic order in the pseudoternary series TbNi_1-xCu_xAl

Neutron diffraction and susceptibility measurements have been performed to investigate the anomalous transition from antiferro-to ferromagnetic order which takes place in the ternary intermetallic compound TbNiAl when Ni is substituted for Cu within the same crystal structure. The transition is anomalous because 1) a few per cent of Cu already suppresses antiferromagnetism, 2) both ferro- and antiferromagnetic types of order coexist in different "domains" in the transition range 0.01 ≤ x ≤ 0.10, and 3) the balance between both types of domains further depends on temperature.