Exchange bias-like effect in TbFeAl induced by atomic disorder

The exchange bias-like effect observed in the intermetallic compound TbFeAl, which displays a magnetic phase transition at T^h _c ≈ 198K and a second one at T^l _c ≈ 154K, is reported. Jump-like features are observed in the isothermal magnetization, M(H), at 2K which disappear above 8 K. The field-cooled magnetization isotherms below 10K show loop shifts that are reminiscent of exchange bias, also supported by the training effect. A significant coercive field, H_c ≈ 1.5T at 2K, is observed in TbFeAl which, after an initial increase, shows a subsequent decrease with temperature. The exchange bias field, H_eb, shows a slight increase and a subsequent leveling off with temperature. It is argued that the inherent crystallographic disorder among Fe and Al and the high magnetocrystalline anisotropy related to Tb³⁺ lead to the exchange bias effect. TbFeAl has been recently reported to show the magnetocaloric effect and the present discovery of exchange bias makes this compound a multifunctional one. The result obtained on TbFeAl generalizes the observation of exchange bias in crystallographically disordered materials and gives impetus for the search for materials with exchange bias induced by atomic disorder.