Dynamic susceptibility study of YFexAl12−x (4 ≤ x ≤ 5)

Linear and nonlinear susceptibility measurements have been performed in YFexAl12−x (x = 4, 4.7 and 5) intermetallic compounds. This study confirms that long-range order only takes place below the transition temperature values, Tc, previously detected by magnetization and Mössbauer data. Antiferromagnetic interactions are dominant for YFe4Al8, however the enhancement of the magnetic susceptibility with iron content evidences that a ferromagnetic-type ordering with increasing strength develops with the replacement of aluminum by iron atoms. The coexistence of competing antiferromagnetic and ferromagnetic interactions gives rise to magnetic frustration, leading to a complex magnetic behaviour dependent on applied field and temperature. For all compositions, including the ordered YFe4Al8, there is evidence of uncorrelated iron-rich nanoclusters with short-range ferromagnetic-like order above Tc.