Metastable magnetic behaviour in UFe₄Al₈

Experimental results of ac susceptibility, dc magnetization, magnetic relaxation, and specific heat measurements on a well annealed polycrystalline UFe₄Al₈ sample establish that this compound is a long-range magnetic exchange interaction-dominated ferromagnet (Curie temperature T_C = 138 K) with strong magnetic anisotropy. The typical metastable magnetic characteristics the irreversibility of the temperature dependence of the magnetization and the long-time magnetic relaxation behaviour at low temperatures - mainly result from domain wall pinning effects. The downshift of the ac susceptibility peak position with increasing frequency suggests that the effect of the spin-glass state, if it exists at all, is rather weak in this system.